Neuro 101 Final

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Testosterone in Humans

treating adults with extra testosterone does not increase their aggression, nor do men going through puberty experience sudden large increase in aggressive activity

TRPV1

type of receptor that reports rise in temperature; responds to spicy foods; (ex: chili peppers evolved capsaicin to ward off mammalian predators by falsely signaling burning heat) Nerve fibers that possess TRPV1 receptors consist of thin, unmyelinated fibers called C fibers Stimulating TRPV1 receptor too much can be hazardous to your health

TRPM3

type of related receptor that detects even higher temperatures than TRPV1, but does not respond to capsaicin; These receptors are found on A delta fibers, which are large-diameter, myelinated axons; because of large axon diameter and myelination, action potentials in these fibers reach spinal cord very quickly Ex: when you burn hand on hot pan, initial sharp pain felt is conducted by thick A delta fibers activated by their TRPM3 receptors, and long-lasting dull ache that follows arises from slower C fibers and their TRPV1 receptors Other TRP Receptors: other members of the TRP family of receptors detect coolness and constituents of species

Interneurons

used to integrate info (ex: bipolar cells in retina) Synaptic activity also means the apoptosis of some cells

William Wootton

was born profoundly deaf; He had cochlear implants at 18 months of age At 4 years of age, he plays with a keyboard, reacts to the sounds of airplanes and trains, while learning still ASL

Supertasters have more bitter receptors

what's the consequence? Bitter tastes are much more powerful to a significant degree; You can either crave it more or gag in response to it Test: use blue food coloring to see if you're a supertaster

Synaesthesia

when coloured sounds taste sweet (beeli et al.) "27 year old professional musician who is female, right-handed and of average intelligence" Whenever she hears a specific music interval, she automatically experiences a taste on her tongue that's consistently linked to that particular interval

Ectodermal dysplasia

when ectodermal cells don't differentiate, migrate, die or synapse normally; or a genetic disorder with different severities; hair, teeth, nails, sweat glands, salivary glands, cranial-facial structure, digits; when ectodermal cells; can result in misshapen and missing teeth (ex: 5 year old girl from Sweden with dominant hypo, or Michael John Berryman, American actor from Star Trek)

Stress

while many different parts of body respond to stress, brain carefully monitors and controls such responses

Medial Temporal Lobe and STM/LTM:

while medial temporal lobe isn't necessary to encode sensory info into STM or to retrieve that info from the STM, it is crucial for moving info from STM into LTM

Mixed Feelings About SSRIs

while modern antidepressant drugs are effective, their effects are modest and evident only in most severely depressed people; other analytic studies have found stronger evidence of clear beneficial effects of SSRIs relative to placebos:

How Olfactory Neurons Differ From Neurons of the Brain

while there's a wide diversity of olfactory receptor protein subtypes (there are hundreds to thousands, three are only a limited number of subtypes of receptors for a particular neurotransmitter in the brain Comparison of Olfactory Receptor Neurons in Humans and Mice: Mice have around 2 million olfactory receptor neurons (each expressing only one of 1,000 different receptor proteins), and these receptor proteins are comprised of four different subfamilies, with have about 250 receptors each (within each subfamily, members have similar structure and recognize chemically similar odors) Humans make around 400 different kinds of olfactory receptor proteins; some of tongue's taste cells have olfactory receptors; we must recognize most odors by their activation of a certain combination of different kinds of receptor molecules (pattern-coding) Two people can differ by about 30% in the makeup of their olfactory receptors Another difference btw olfactory and brain neurons is that olfactory neurons die and are replaced in adulthood Olfactory Bulb: each olfactory neuron extends a thin, unmyelinated axon into the nearby olfactory bulb of the brain Olfactory bulb is an anterior projection of brain that terminates in upper nasal passages and, through small openings in the skull, provides receptors for smell Glomerulus: The olfactory neurons that extend their axons into the olfactory bulb each terminate on one specific glomerulus, which is a spherical clump of neurons; thousands exist in olfactory bulb Each glomerulus receives inputs exclusively from olfactory neurons that express the same type of olfactory receptor Olfactory receptor proteins found on axons of these cells guide the zxons to their corresponding glomeruli

Visual Field

whole area that you can see without moving your head or eyes

Fear-Conditioning

work in animals has revealed that fear conditioning, or memory for a stimulus that the animal has learned to associate with negative event involves the amygdala and brainstem pathways; Such studies suggest that persistence of memory and fear in PTSD may depend on failure of mechanisms to gorget; There's also a hormonal linke; people with PTSD exhibit long-term reduction in cortisol, due to persistent increases in sensitivity to cortisol (they feel effect of stress hormones more strongly, which might repeatedly retrigger fear response, making it harder to forget stressful events):

LTP

you are potentiating the circuit so that it'll be more accurate; increasing the potential of that circuit to be activated Occurs in dentate gyrus, CA1 and CA3 regions of hippocampus:

"Hearing impairment" and "hearing loss" are often used interchangeably by health care professionals to refer to below normal threshold levels

"Hard of hearing" is more functional than audiologic "Deaf" (small "d") is a colloquial term that implies hearing threshold in the severe-to-profound range by audiometry Deaf culture (always capital "d"): cultures are characterized by unique social and societal attributes; Members of the Deaf community (i.e., the Deaf) don't consider themselves to be hearing "impaired," nor do they feel that they have a hearing "loss" rather, they consider themselves deaf Their deafness is not considered to be a pathology or disease to be treated or cured

Pain is the discomfort associated with tissue damage and is a protective form of somatosensation

"Pain is an unpleasant sensory and emotional experience that's associated with actual or potential tissue damage or described in such terms." - International Association for the Study of Pain Pain is termed nociceptive (nocer - to injure or to hurt in Latin), and nociceptive means sensitive to noxious stimuli (stimuli that elicits tissue damage and activates nociceptors) Noxious stimuli are stimuli that elicit tissue damage and activate nociceptors Nociceptors are free (bare) nerve endings in skin, muscle, joints, bone and viscera (not CNS); release chemicals in response to direct damage tissue and threat of damage Nociceptors have TRP channels (like voltage gated K+ channels) that transduce noxious stimuli to action potentials TRPV1 receptors are thin C fibers that conduct slowly, producing lasting pain; responds to capsaicin (chemical in spicy food) TRP2 receptors are A delta fibers, large myelinated axons, that register pain quickly

Three Mechanisms That Enable Us to Deal With Varying Intensities of Light

(1) Adjusting Size of Pupil To Deal With Varying Intensities of Light: One way the visual system deals with large range of intensities is by adjusting the size of the pupil (opening in the colorful disc called the iris); Pupil Dilation: dilation of pupils is controlled by sympathetic division of autonomic system (constriction is controlled by the parasympathetic division) Drugs that block acetylcholine transmission in parasympathetic synapses onto muscles controlling iris relax them and thus open the pupil widely (ex: ecstasy) Pupil Constriction: In bright light, pupil contracts quickly to admit a small proportion of the light that is does when light is dim (2) Range Fractionation: Main reason we can see over vast range of light intensities; the handling of different intensities by different receptors; some with low thresholds (rods) and others with high thresholds (cones); range fractionation is the means by which sensory systems cover wide range of intensity values, as each sensory receptor cell specializes in just one part of the overall range of intensities (3) Photoreceptor Adaptation: tendency of rods and cones to adjust their light sensitivity to match current levels of illumination; mechanism in which each photoreceptor constantly adjusts its sensitivity to match the average level of ambient illumination, over a wide range This demonstrates that the visual system concerns differences/changes in brightness rather than absolute levels of brightness The photoreceptor operates over range of intensities, and they constantly shift their whole range of response to work with prevailing levels of illumination

Inputs from auditory nerves distributed in both sides of brain via an ascending network

(1) First, auditory nerve fibers terminate in the cochlear nuclei, where initial processing happens; (2) Output from cochlear nuclei primarily projects to the superior olivary nuclei, each of which receives inputs from both right and left cochlear nuclei; this bilateral input makes superior olivary nucleus first brain site at which binaural (two-ear) processing occurs: Superior Olivary Colliculi: Brainstem nuclei that receives input from both right and left cochlear nuclei and provides the first binaural analysis of auditory info (3) Superior olivary nuclei pass info derived from both ears to inferior colliculi, which are primary auditory centers of midbrain; (4) Outputs of the inferior colliculi go to the medial geniculate nuclei of the thalamus, and outputs from medial geniculate nuclei extend to several auditory cortical areas

AMPA/NMDA Receptors in Response to a Tetanus (Postsynaptic Changes):

(1) If larger quantities of glutamate are released from presynaptic cell in response to a barrage of action potentials caused by a tetanus, this stronger stimulation of the AMPA receptors depolarizes the postsynaptic membrane so much that the Mg2+ plug is repulsed from the NMDA receptor's channel (2) Now NMDA receptors are also able to respond to glutamate, admitting large amounts of Ca2+ into the postsynaptic neuron; Thus, NMDA receptors are fully active only when 'gated' by a combination of strong depolarization (via AMPA receptors) and the ligand (glutamate) (3) The large influx of Ca2+ at NMDA receptors activates various intracellular enzymes that affect AMPA receptors in three ways (so that after the tetanus there are more AMPA receptors and these AMPA receptors are more effective, so that the synaptic response to glutamate is strengthened--i.e. The synapse is more responsive/postsynaptic cell has a stronger response): First, the enzymes cause existing nearby AMPA receptors to move to the active synapse Second, they modify the AMPA receptors to increase their conductance of Na+ and K+ ions; Third, more AMPA receptors are produced and inserted into the postsynaptic membrane

How Special Neural Pathways Carry Pain Info to the Brain:

(1) Nerve fibers carrying info about pain and temperature send their axons to dorsal horns of spinal cord; (2) where they synapse onto spinal neurons that project across the midline to the opposite side, and then up toward the thalamus, forming the anterolateral system Anterolateral System/Spinothalamic System: A somatosensory system that carries most of the pain and temperature info from the body to the brain; in this system, each hemisphere receives inputs from opposite side of body (3) Within spinal cord, arriving pain fibers release the excitatory transmitter glutamate an a peptide called substance P that boosts pain signals and remodels pain pathway neurons Substance P: A peptide transmitter that's involved in pain transmission; mice lacking substance P can't feel intense pain, only mild pain (4) Pain info is eventually integrated in cingulate cortex (part of limbic system) Cingulate Cortex/Cingulum: Region of medial cerebral cortex that lies dorsal to the corpus callosum Extent of activation in cingulate (and somatosensory) cortex correlates with how much discomfort different people report in response to the same mildly painful stimulus Different subregions of cingulate cortex mediate emotional vs. sensory aspects of pain

Neural Signals Travel From Retina to Several Brain Regions

(1) Retinal image is inverted and reversed right to left compared to the visual field; photoreceptor cells send signals to bipolar cells, which send signals to ganglion cells of the eye (2) Ganglion cells in each eye produce action potentials that are conducted along their axons to send visual info to the brain (these axons compose the optic nerve/cranial nerve) The axons of the optic nerve bring visual info into the brain, eventually reaching the occipital cortex at the back of brain: (3) At the optic chiasm, axons from temporal halves of each retina continue into optic tract on same side; axons from nasal haves cross to the optic tracts on the opposite side Optic Chiasm: The point at which parts of the two optic nerves cross the midline; note: more axons cross midline in prey animals, giving them a wide field of view at the expense of poor depth perception because of the small overlap in their fields of vision; thus predators have greater depth perception because they have larger overlap in their fields of vision The result of this crossover is that the right hemisphere of brain "sees" left side of visual field, while left hemisphere "sees" right side of visual field (4) After axons of terminal ganglion cells pass optic chiasm, they are known as the optic tract; A few retinal ganglion cells in optic tract send axons to the superior colliculus in the midbrain (produces rapid movements of eyes toward a target and controls pupil's response to light levels) Most axons of optic tract terminate on cells in the lateral geniculate nucleus (LGN), which is the visual component of the thalamus Lateral Geniculate Nucleus (LGN): Part of the thalamus that receives info from the optic tract and sends it to visual areas in the occipital cortex (5) Axons of LGN neurons form optic radiations, which terminate in the primary visual cortex of the occipital cortex at the back of the brain Optic Radiations: Axons in the LGN that terminate in primary visual areas of the occipital cortex Occipital Cortex: Also called the visual cortex; this is the cortex of the occipital lobe of the brain, corresponding to the visual area of the cortex Primary Visual Cortex (V1)/Striate Cortex: The region of the occipital cortex where most visual info first arrives; also called striate cortex because cross sections of brain tissue from this region feature a stripe/striation, correspond to convergent binocular inputs; the binocular input to layer IV of primary visual cortex is important for depth perception Visual cortex in right cerebral hemisphere receives input from left half of visual field, while visual cortex in left hemisphere receives input from right half of visual field

How Hair Cells Transduce Movements of the Basilar Membrane into Electrical Signals

(1) Rippling of basilar membrane is converted into neural activity through actions of the hair cells (each hair cell features a sloping brush of miniscule haris called stereocilia on its upper surface, nestled into the tectorial membrane that lies above; (2) Hair cells form bridge between two membranes that bends when sounds cause basilar membrane to ripple (3) Even tiny bend of stereocilia produces large and rapid depolarization of the hair cells; this results from nonselective ion channel on stereocilia, which pop open as stereocilia bend, allowing inrush of K+ and Ca2+ ions; (4) This depolarizes causes rapid influx of Ca2+ at base of hair cell, which causes synaptic vesicles there to fuse with presynaptic membrane and release neurotransmitter, stimulating adjacent nerve fibers; (5) Stereocilia channels close again right after depolarization; this rapid on-off switch allows hair cells to track quick oscillations of basilar membrane with great sensitivity

Scala Tympani (Tympanic Canal)

(1) Within the cochlea, when ossicles transmit vibrations from tympanic membrane to oval window, waves or ripples are created in fluid of scala vestibuli; (2) Which cause basilar membrane to ripple; basilar membrane is tapered (wider at apex of cochlea than at the base); because it's tapered, each successive location along basilar membrane shows its strongest response to a different frequency of sound; High frequencies have greatest effect near base, where basilar membrane is narrow and stiff Lower frequency sounds produce larger response near apex, where basilar membrane is wider and floppier

Cochlear implants are for which type of deafness?

(B) Sensorineural Culturally-sensitive descriptions (shearer et al. 1999) Blake Wilson, PhD Co-director at duke, Hearing Center helped develop cochlear implants

How the Sensory Cortex is Highly Organized

(each cortical sensory region processes different aspects of our perceptual experiences): Primary Sensory Cortex: For each sensory modality, there is a designated region (ex: primary somatosensory cortex, primary auditory cortex, etc.) on the primary sensory cortex that is generally the initial destination of sensory inputs to the cortex Primary Somatosensory Cortex: Also called somatosensory 1 or s1; the primary somatosensory cortex of each hemisphere is located in postcentral gyrus (long strip of tissue that lies posterior to central sulcus, diving parietal lobe from frontal lobe) Cells in S1 are arranged as map of body, where size of each region on the map is proportional to density of sensory receptors found in that region of the skin (ex: parts of body where we're very sensitive to touch have large representations in S1 compared with less sensitive areas): Non-Primary Sensory Cortex: However, cortical regions other than primary sensory cortex may receive and process the same info, often in collaboration with primary sensory cortex

Two Groups of Bipolar Cells and Their Properties

(each type differs in the glutamate receptors they possess): On-Center Bipolar Cells: A group of bipolar cells are inhibited by glutamate release, and thus they are excited by light in the center of their receptive field (because light causes photoreceptor to release less glutamate); glutamate is inhibitory to on-center bipolar cells Off-Center Bipolar Cells: A group of bipolar cells are excited by glutamate release, and thus they are inhibited by light in the center of their receptive fields, and stimulated by darkness; turning off a light at the center of its receptive field excites it (glutamate is excitatory to off-center bipolar cells)

Facial feedback hypothesis

(it's not well studied) = feedback from our face muscles directly affect our emotional experience; the idea is that there's some bottom-up control from your experiences Which of the following does the facial feedback hypothesis support the most? The James-Lange Theory; the idea is that changing physiology is going to lead to the emotion

Six Stages of Cellular Nervous System Development

(note: there's a lot of overlap and integration between these steps): Neurogenesis: the mitotic division of neuronal cells to produce neurons Cell migration: massive movement of nerve cells or their precursors to establish distinct nerve cell populations (nuclei in the CNS, layers of the cerebral cortex, etc.) Cell differentiation: the refining of cells into distinctive types of neurons or glial cells Synaptogenesis: the establishment of synaptic connections as axons and dendrites grow Neuronal cell death: the selective death of many nerve cells Synapse rearrangement: the loss of some synapses and the development of others to refine synaptic connections, which extends throughout our lifespan

Types of Memory

(we know that there are multiple distinct memory systems because of famous case studies; some famous patients lost specific types of memory):

Brain Structures Important for Declarative Memory:

**Brain circuit that includes the hippocampus, mammillary bodies, and dorsomedial thalamus is indispensable towards the formation of new declarative memories; however, pre-established declarative memories (formed before brain damage) aren't stored in these structures for l Experiment Conducted to Determine These Structures: To determine which parts of the temporal lobe are important for declarative memory, researchers removed specific parts of temporal lobes of monkeys; Through this procedure, they determined that the amygdala isn't crucial for declarative memory, but that the hippocampus is; Impairment of declarative memory was even worse when hippocampal damage was paired with lesions of nearby cortical regions that communicate with the hippocampus (entorhinal, parahippocampal, and perirhinal cortices); thus, humans are more impaired when both the hippocampus and medial temporal cortex are damaged These experiments indicated that we need at least one functioning temporal lobe (including hippocampus)--i.e. the hippocampus and the nearby cortex--to make new declarative memories; **these aren't the only brain structures needed for new declarative memories, however

Resetting Patterns Changes Memories

**Overall finding: after interrupted videos, resetting the hippocampal patterns lead to more false memories later Surprise disrupted pattern of current train of thought and makes you focus your attention externally to learn new information:

Synaptic Plasticity

- change in physiology, structure or both Several diff changes can result in a more effective synapse; An interneuron modulates polarization of the axon terminal and causes the release of more transmitter molecules per nerve impulse A more frequently used neural pathway takes over synaptic sites formerly occupied by a less active competitor; A neural circuit that's used more often increases the number of synaptic contacts This is showing that maybe more interneurons are going to appear as a result of synaptic plasticity LTP: you are potentiating the circuit; increase the potential of that circuit to be active There are bipolar neurons located in the retina; maybe more interneurons will appear as a result of synaptic plasticity

The amygdala is critical to emotional learning

- forming associations between emotional responses and specific memories of stimuli Does not very take very long for a rat, and therefore, a human, to have emotional learning; it's almost like one-trial learning; They found that lesioning the central nucleus in the amygdala prevents increase of blood pressure and freezing behavior Amygdala is also important for appetitive learning The central nucleus is separated from the lateral nucleus; stimulus picture goes to the sensory organs, the eyes, sends it to the thalamus of the relay station, and then there's a low road and a high road (low means it doesn't go to the cortex)

Universal facial expressions of emotions

-- across cultures and other animals; Researchers have boiled them down to a few; Almost all species of animals engage in aggressive behaviors, and they're species specific (ex: there's posturing, biting, hissing, etc. and this is directly linked to their genetic code; there are genes that have been identified that translate into different receptors) You probably shouldn't let a baby cry for awhile, because crying can reflect many different types of emotions Age does matter in thinking about communication styles By processing many hours of videos of mice in varying emotional circumstances, a computerized AI system learned to categorize the six subtle-but-distinct mouse facial expressions shown; the facial expressions were associated with activity in brain mechanisms known to be involved in emotion in humans In a particular study, 26 participants were videotaped under three conditions with their arms submerged in water to cause the pain or fake pain; The first condition was the baseline (where water was 20 degrees celsius, very comfortable), and then they posed the pain at 20 degrees celsius to fake pain Then, the real pain was at 2 degrees celsius They took naive human subjects to do a two-alternative choice of fake or real and human subjects were not good at it; naive human subjects were 52% correct (chance) at differentiating posed from real pain Why are we so bad at this? Theory: we evolved to be very sensitive to any signs of danger -- we err on the side of assuming danger so we are on alert to experience fear above all other emotions

"How Covid-19 Causes Loss of Smell" Article

Best way to suppress hunger or craving for food is to plug up your nose Gustatory cortex, olfactory cortex, visual cortex, somatosensory cortex, auditory cortex Some cranial nerves of interest this week: Olfactory Vagus Vestibulocochlear Facial

Explain the "three cautions as we approach this course content."

1. Ideas about thinking and emotion date back to earlier recorded civilizations --ancient Egyptians and Greeks -- they are based on archeological evidence, and therefore these ideas are very patchy 2. The history of medicine is hugely biased toward Western historical documentation, so this is inherently how we describe this perspective 3. Attitudes to animal and human experiments were very different in the past and are quite unpleasant, thus would unlikely be allowed today

Three Stages of Memory:

1. Sensory buffers 2. Short term memories 3. Long term memories

Five Different Types of Nondeclarative Memory:

1. Skill learning 2. Priming 3. Classical conditioning 4. Nonassociative learning 5. Spatial memory

Cognitive and identity diversity

1. the key to learning, problem-solving and development, which our course structure supports 2. The Diversity Bonus: General idea is that if you have a problem that's difficult, the notion of individual ability becomes problematic; rather, if you know different tools than I do, there's a diversity bonus (different ways of thinking, different heuristics, different perspectives); think of people as toolboxes, rather than numbers; the best team might not have the best individuals in it, but might come together to form something greater Cognitive Diversity: consists to things like information, knowledge, heuristics, rules of thumb, causal models, and frameworks Cognitive diversity comes from different training and experiences, but also from identity Identity Diversity: race, gender, sexual orientation, religion, physical abilities Through cognitive diversity, identity diversity produces outcome; training differences and identity differences both matter Ex: if a group of people are sitting at a table, and one person thinks of eight ideas, but another person thinks of 10 different ideas, that's a bonus; second-level bonus comes in when we can take one individual's idea and another individual's idea and then combine them to create something new Ex: the Thursday component of our course, with tRAs and AAs, implements the diversity bonus, as there is both cognitive and identity diversity present The idea is to shift people's frame of reference; think of who are the people who have germane knowledge?

G-coupled proteins

2nd messenger systems that take a little bit longer and cause the channel to cascade

Photopic vision

4.5 million cones

Scotopic vision

91 million rods

**Long-term depression (LTD)

= another activity-dependent synaptic change; may help underlie symptoms of withdrawal from drug addiction **BONUS on testlet two: video about long-term depression Memories are stored in neurons, synapses and circuits in brain regions Strong and weak evidence support this biological bases for memories (somatic examples = genetically modified NDMA mice perform differently, behavioral examples = training leads to 'behavioral LTP' and correlational studies = LTP and memory formation time course match) Memory has been analyzed at multiple levels using many techniques

Six Basic Steps for LTP

= physical change to your brain: LTP is required to make some protein that is necessary for long-term changes physiologically Nitric oxide: goes back to presynaptic cell so it can release more glutamate At baseline, normally, **the NMDA channel is blocked by a Mg2+ molecule ad only the AMPA channel functions in the exciting the neuron; there's a baseline of low-level activity With repeated activation of the AMPA receptors, depolarization of the neuron drives Mg2+ out of the NMDA channel, allowing Ca2+ ions in The rapid entry of ca2+ ions through the NMDA receptor triggers second-messenger systems that lead to LTP, increasing the effectiveness of existing AMPA receptors and moving more into the membrane; Retrograde transmitters, perhaps nitric oxide, reach the presynaptic terminal to enhance neurotransmitter release These changes make the synapse more responsive The postsynaptic cell now has a stronger response, as more transmitter is released and more AMPA receptors are activated Tetanus = spike of activity NMDA and AMPA are receptors on postsynaptic neurons During normal low-level activity what produces the ESPSs? Glutamate binding to AMPA What does nitric oxide do? Increases glutamate release, increases synaptic strength Hebbian synapse: neurons that fire together, wire together, but not always (**this is not the whole story; because plasticity changes across development, stimuli are not all created equally and circuits vary in complexity):

Medial Forebrain Bundle

= reward circuit (not enough to say it's the emotional circuit); includes the hypothalamus, which informs the presence of rewards, acts on VTA (ventral tegmental area), autonomic and endocrine functions via the pituitary gland. VTA and nucleus accumbens are MFB main circuits (mesolimbic pathway); The MFB is dopamine-rich:

Amusia

A disorder characterized by the inability to discern or sing tunes accurately; associated with abnormal function in right frontal lobe and deteriorated connectivity between frontal and temporal cortex, the result of which is an inability to access pitch info even though cortical pitch-processing systems are still intact Studies of people with amusia indicate that we process pitch and rhythm separately when listening to music

Post-Traumatic Stress Disorder (PTSD)

A disorder in which memories of an unpleasant episode repeatedly plage the person 19% Vietnam War veterans had PTSD some point after service Among those veterans exposed to intense war zone stressors, over 35% developed PTSD at some point, still having symptoms decades later

AMPA Receptors

A fast-acting ionotropic glutamate receptor that also binds the glutamate agonist AMPA

Classical Conditioning

A form of associative learning (learning that involves relations between events) in which an originally neutral stimulus has power to elicit a conditioned response (ex: dog learning to salivate when presented with auditory of visual stimulus matched with the presentation of food--ringing of bell) Involves the unconditioned stimulus (US)-meat powder- unconditioned response (UR)-the salivation-conditioned stimulus-bell-ringing-and conditioned response Amygdala and cerebellum are involved in classical conditioning (ex: while people with hippocampal lesions can have the conditioned eye-blink response, people with damaged cerebellums can only acquire it on the side where the cerebellum is intact) Instrumental Conditioning/Operant Conditioning: A learning process in which behavior is modified by the reinforcing or inhibiting effects of the resulting consequences An association is formed between the animal's behavior and the consequences of that behavior (ex: in Skinner box experiment, animal learns that a certain action--pressing a bar--is followed by a reward--food pellet) Nonassociative learning involves reflex pathways

NMDA Receptor:

A glutamate receptor that also binds the glutamate agonist NMDA and that's both ligand-gated and voltage-sensitive; these receptors are on the postsynaptic cell

Define neurophysiology, neuroscience, and how they contribute to studying the biological bases of behavior.

A lack of sleep will age a man by a decade; there is an equivalent detrimental effect in female reproductive health You need sleep after learning to save those memories You also need sleep before learning to prepare your brain for info absorption; without sleep, the memory circuits of the brain become waterlogged Two experimental group: sleep group and sleep deprivation group, then placed both groups inside an MRI scanner and have them learn a series of facts; found that there was a 40% deficit in the ability of the brain to make new memories due to lack of sleep Hippocampus is good at receiving new memory files and holding on to them In the study, couldn't find any activity in the hippocampus Discovered that there are powerful brain waves that happen during the deepest stages of sleep, with powerful reservoirs lying on top of them called "sleep spindles" and it's the combined quality of these brain waves that act like a file transfer mechanism at night, transferring memories from short term to more long-term A physiological feature of aging is that your sleep gets worse The disruption of deep sleep is an underappreciated factor that is contributing to cognitive decline Sleeping pills are blunt instruments Direct current brain stimulation: insert small amount of voltage into brain, and if you apply this during sleep, you can amplify the size of deep-sleep brain waves and enhance memory retention When we lose one hour of sleep on daylight savings in the spring, there is an increase in heart attacks, but in the winter, when you add an hour in the winter Immune system and sleep: when you're not sleeping enough, there's a reduction in immune cell activity; there was a 70% drop in natural killer cell activity Sleep deprivation increases risk of developing bowel and breast cancer; can even erode your DNA genetic code In a study, change in gene activity was measured after lack of sleep, and some genes were switched off by lack of sleep, such as immune system genes, those activated were those associated with tumors, stress, and cardiovascular disease Regularity is key; keep sleeping hours consistent, and also sleeping in cooler temperatures Neuroscience: study of the nervous system; not just brain and spinal cord, but also all of the pieces that come off of the spinal cord; involves all we feel and choose to feel; Nervous system is what governs our body; to optimize and integrate that organ function, you want to be able to have the nervous system help decide what it should do Neuroscience is the study of the nervous system spans many disciplines, and is analyzed at multiple levels Neurophysiology is the study of how neurons work: circuit, cellular, synaptic and molecular levels

Amnesia:

A partial or total loss of memory, usually result of accident or disease

Memory Trace:

A persistent change in the brain that reflects the storage of memory Memory trace established doesn't merely deteriorate from passage of time; these memories must actively suffer interference from events before or after formation

Long-Term Potentiation (LTP)

A stable and enduring increase in the effectiveness of synapses following repeated strong stimulation; LTP occurs in the hippocampus; long-lasting change in synaptic strength LTP can be produced in conscious and anesthetized animals and in isolated slices of brain; occurs in both invertebrates and vertebrates Once induced by a tetanus, LTP can last for weeks or longer A consequence of LTP: more AMPA receptors on postsynaptic neuron Three pathways in hippocampal formation where LTP occurs: Perforant pathway (entorhinal cortex to dentate gyrus) Mossy fiber pathway (dentate gyrus to CA3 pyramidal cells) Shaffer collaterals (CA3 pyramidal cells to CA1 pyramidal cells)

Emotion

A subjective mental state that's usually accompanied by distinctive cognition, behaviors, and physiological changes They are evolved programs that guide our responses to daily threats and opportunities Emotion may influence, and be influenced by, cognitive processes like memory and attention (ex: rapidly beating heart, sweating, etc.)

Pure tone

A tone with a single frequency of vibration; (ex: because sound produced by loudspeaker has only one frequency, it's pure tone and can be represented by sine wave; pure tone can be described in terms of: Amplitude: also called intensity; measured as sound pressure in dyn/cm2; perception of amplitude is loudness, expressed as dB; dB scale is logarithmic, and one decibel is threshold for human hearing When different instruments play same note, notes differ in relative intensities of various harmonics Additionally, subtle qualitative differences between instruments give each its characteristic timbre Frequency: number of cycles per second; measured in Hz (ex: A on piano has frequency of 440 Hz); perception of frequency is pitch)

Sensory Buffers:

A very brief type of memory that stores the sensory impression of a scene; in vision, it's called 'iconic memory' (ex: fleeting impression of glimpsed scene that fades from memory seconds later

Analgesia

Absence of or reduction in pain

How Activation of Endogenous Opioids Relieves Pain

Acupuncture: In people for whom acupuncture is effective, release of endorphins is important part of this process (we know this because naloxone often blocks acupuncture's effectiveness) Acupuncture largely resembles placebos; expectation that needles will relieve pain is important, inducing release of endogenous opioids Stressful life events can produce analgesia; animal research indicates that stress activates both an opioid-dependent form of analgesia (which can be blocked by naloxone) and another system that relies on endocannabinoids Such endogenous analgesic systems allow wounded person to fight or escape rather than be subsumed by pain Types of Pain Relief:

Symptoms of Consuming Excessively Spicy Foods

After eating "Carolina Reaper" pepper, 6 times hotter than habanero, man suffered dry heaves and neck pain, followed by series of serious headaches While MRI scans of his brain showed no abnormalities, CAT scan of blood vessels revealed that several arteries supplying his brain had narrowed extremely, causing the headaches

How Olfactory Info Projects From the Olfactory Bulbs to Several Brain Regions

After having received info from many olfactory neurons expressing same type of olfactory receptor, glomerulus, then tunes and sharpens the neural activity associated with the corresponding odors; Glomeruli are organized within olfactory bulb according to topographic map of smells (neighboring glomeruli receive inputs from receptors that are closely related) Thus, spatial organization of glomeruli within olfactory bulbs reflects segregation of four receptor protein subfamilies in olfactory epithelium Olfactory info is conveyed to the brain via axons of mitral cells, extending from glomeruli in olfactory bulbs to various regions of forebrain; Smell is only sensory modality that synapses directly in the cortex, rather than passing through the thalamus Targets for olfactory inputs include the hypothalamus, amygdala, and prepiriform cortex (these limbic structures are closely involved in memory and emotion as well)

DISC1 Gene

Disabled version of the gene DISC1 is associated with schizophrenia; DISC1 protein normally regulates trafficking of molecules within neurons When researchers inserted the schizophrenia-associated mutant version of DISC1 into mice, found that mice developed enlarged lateral ventricles reminiscent of enlarged ventricles in people with schizophrenia:

How Brain Circuits Mediate Aggression

Aggressive behavior in various animals (including humans) is modulated by brain activity associated with several neurotransmitter systems including dopamine, GABA, vasopressin, and especially serotonin Inhibitory Role of Serotonin in Aggression: Research found that most aggressive monkeys had lowest levels of serotonin being released in brain, and mice that lack specific subtype of serotonin receptor are hyper aggressive Drugs that enhance GABA transmission generally reduce aggressive behavior in humans (in minority of users, however, they occasionally provoke aggression) Role of Activation of VMH in Aggression: A portion of the amygdala that receives olfactory and pheromonal info; this info is relayed to the ventromedial hypothalamus (VMH), which serves as a trigger to activate aggressive behavior Using techniques to inhibit VMH activity reduces likelihood of attack, and vice versa Maternal Aggression: females are also aggressive ati times, particularly when caring for their young; typically studied by introducing intruder mouse into cage of a nursing mother, and in these cases, she may immediately attack intruder Maternal aggression is also controlled by neural circuits in the VMH, along with other regions such as the preoptic area (POA) and premammillary nucleus

Receptor Cells

All animals have sensory organs containing receptor cells that sense some forms of energy, called stimuli, but not others Receptor cells act as filters that convert key stimuli into electrical signals Info from sensory receptors floods the brain in barrage of action potentials travelling along millions of axons

Brain Sites that Support Self-Stimulation Responses

Almost all of these sites are subcortical and are especially concentrated in large axon tract that ascends from midbrain through hypothalamus: the medial forebrain bundle Medial Forebrain Bundle: A collection of axons traveling in the midline region of the forebrain Nucleus Accumbens: an important destination for axons of medial forebrain bundle s the nucleus accumbens, major component of brain's reward circuitry; release of dopamine into nucleus accumbens produces very pleasurable feelings One theory is that electrical stimulation taps into dopaminergic circuits that are normally activated by behaviors that produce pleasurable feelings

Stage 5: Neuronal Cell Death

Also called apoptosis, it's the developmental process during which "surplus" cells die; cell death is crucial phase of brain development, as it's part of the sculpting process in emergence of other tissues in animals and plants During early development, number of cells that die is very large (in some regions of brain and spinal cord, most of young nerve cells die during prenatal development) These cells are dying not because of defect, but our chromosomes carry 'death genes,' (expressed when cell undergoes apoptosis); ex: interfering with death genes in fetal mice causes them to grow brains too large to fit in skull Viktor Hamburger's Experiment: In 1958, Hamburger first described naturally-occurring neuronal cell death in chicks (nearly half of the originally-produced spinal motor neurons die before chick hatches, and same loss of spinal motor neurons was later found in humans): Role of Neurotrophic Factors in Cell Death: Neurons compete for connections to target structures, and cells that make adequate synapses remain, but those without a place to form synaptic connections die Cells compete not just for synaptic sites, but for chemicals that the target structure makes and releases Neurotrophic Factors: Neurons that receive enough of this chemical survive; these target-derived chemicals are called neurotrophic factors (or trophic factors), because they are essentially "feeding" the neurons to help them survive

Stage Six: Synapse Rearrangement:

Also called synaptic remodeling, the loss of some synapses and development of others; refinement of synaptic connections that's often seen in development; not all neurons produced by developing pering are retained into adulthood (some synapses formed early in development are later retracted); some original synapses are lost, and many new ones are formed Synapse rearrangement usually takes place after period of cell death By end of cell death, each surviving motor neuron innervates many muscle fibers, and every muscle fiber is innervated by several motor neurons, but later, surviving motor neurons retract many of their axon collaterals until each muscle fiber comes to be innervated by only one motor neuron; which synaptic connections are retained and which new ones are formed is dependent on competition for trophic factors during development Net Loss of Synapses Can be Adaptive: In human cerebral cortex, there's a net loss of synapses from late childhood until mid adolescence (demonstrated by the thinning of cortical gray matter as pruning of dendrites and axon terminals progresses; this thinning process continues in a caudal-rostral (posterior-anterior) direction during maturation, so prefrontal cortex matures last (which is why adolescents are impulsive) What Determines Which Synapses Are Lost: An important influence is neural activity; one theory is that active synapses take up some neurotrophic factor that maintains the synapse, while inactive synapses get too little trophic factor to remain stable; intellectual stimulation contributes and teens with highest IQ show a prolonged period of cortical thinning

Ear Canal

Also called the auditory canal; tube leading from pinna to tympanic membrane

Spatial-Frequency Model

Alternative proposed to flawed hierarchical model; Model of visual perception that emphasizes the analysis of the different spatial frequencies present in various orientations and parts of a visual scene Says that the visual system analyzes the number of cycles of light-dark or color patches in any stimulus (some narrow, some broad, some oriented vertically, others horizontally, etc.) If they are optimized to detect light-dark cycles, they should respond to repeating bars of light even better than single bar of light This suggests that, rather than specifically detecting semi-naturalistic features as bars and edges, the system breaks down complex stimuli into their individual spatial-frequency components (in such a system, we would require view of whole face, including low-frequency components, which explains why neurons don't respond to only small portions of face, because these only contain high-frequency components)

Amblyopia Treatment

Amblyopia is the reduced visual acuity of one eye that's not caused by optical or retinal impairments; misalignment of two eyes (lazy eye) can lead to this condition, in which acuity is poor in one eye even though the eye and retina are normal; In this condition, if the two eyes aren't aligned properly during first few years of life, primary visual cortex of child suppresses info arriving from one eye, so that eye becomes blind However, most cases of amblyopia are avoidable; balance of eye muscles can be surgically adjusted to bring two eyes into better alignment Also, if weak eye is given regular practice, with the good eye covered, vision can be preserved in both eyes; Optimal treatment for this condition involves a combination of both surgical correction and eye patches

Twin Studies and Schizophrenia

Among identical (monozygotic) twins, if one twin develops schizophrenia, other twin has about fifty-fifty chance of also developing the disorder (concordance of 50%); However, in fraternal (dizygotic) twins, this concordance (sharing of a characteristic) drops to 17% High concordance in identical twins is strong evidence of genetic factor in schizophrenia; however, genes alone can't fully explain whether person will develop schizophrenia (environmental influences account for the 50% of identical twin pairs that are discordant) Subtle neurological signs, such as impaired motor coordination, etc. can be telling; *in sum, twin studies reveal that schizophrenia has both environmental and genetic origins

Describing sounds and people's hearing

Amplitude (physical) on y axis, and frequency (physical on x-axis); there's a little bit of a slope; translates to high pitches being heard best at base of cochlea, and vice versa for other side of cochlea:

Glutamate:

An amino acid transmitter, the most common excitatory transmitter Treatment with drugs that selectively block NMDA receptors prevents new LTP in this region, but doesn't affect synaptic changes that have already been formed These NMDA receptors are largely responsible for LTP, but work in conjunction with other glutamate receptors called AMPA receptors;

Obsessive-Compulsive Disorder (OCD)

An anxiety disorder in which affected individual experiences recurrent unwanted thoughts and engages in repetitive behaviors without reason or the ability to stop Symptoms progressively isolate person from ordinary social engagement:

Long-Term Memories (LTMs):

An enduring form of memory that lasts days, weeks, months, or years; LTM has a very large capacity

Serious defects of the neural tube (2 conditions)

Anencephaly: parts of baby's brain and skull don't form directly, born without forebrain and cerebrum, almost always die upon birth; 1 in 400 babies born with this Spina bifida: serious birth defect in which spine does not form correctly When we talk about neurogenesis, we're usually talking about the hippocampus; neurogenesis is greater with enrichment Adult neurogenesis in dentate gyrus of the hippocampus is greater with enrichment In 1990s, researchers had new methods to trace neurogenesis over time, so they could tag cell in dentate gyrus on day 1, and then follow to see if this is going to turn into a neuron There are three different layers in the dentate gyrus that you can look at Running increases cell proliferation and neurogenesis in the adult mouse dentate gyrus; this study came out in 1999 In this study, they found that just after day 1, there's a significant difference of new neurons Took mice and put them in three different conditions: Neurogenesis in the adult human hippocampus (Erikson et. al): post-mortem tissue from 5 cancer patients shows ability of adult brains to generate new neurons in different layers of the dentate gyrus; it's not a lot (not as much as we see in mice) and there's no association to behavior/cognitive performance or environmental conditions They labeled tissue and injected it and followed it over time: The layer of gray matter on the surface of the cortex gets thinner throughout development, as synapses are retracted; this is why 12 year olds are more impulsive than 18 yr olds Retraction of synapses early on and prefrontal cortex matures in adolescence

Benzodiazepines

Any of a class of antianxiety drugs that are noncompetitive agonists of GABA receptors in central nervous system (ex: diazepam is one of most prescribed drugs in history; other include Xanax, Halcion, and Ativan) Anxiolytic benzodiazepines interact with binding sites part of GABA receptors (especially GABAA receptors, where they act as noncompetitive agonists; As GABA is most common inhibitory transmitter, when it's released from presynaptic terminal, it hyperpolarizes target neuron and inhibits it from firing; when benzodiazepines are present, GABA produces enhanced hyperpolarization; this boosts GABA-mediated postsynaptic inhibition, reducing excitability of postsynaptic neurons Neurosteroid allopregnanolone interacts with benzodiazepine binding site on GABA receptor (brain makes its own anxiety-relieving substance)

Neurons in Visual Cortex Beyond Area V1

Area V1 represents only small proportion of total amount of cortex devoted to vision; from V1, axons extend to cortical areas V2 and V2 and the inferior temporal area (the receptive fields of these are more complex than those of area V1) Areas that are largely or entirely visual in function occupy about 30% of human cortex Area V2: Adjacent to V1, many of its cells have similar receptive fields to those of V1; V2 cells can respond to illusory contours (as shown below), responding to complex relations among parts of their receptive fields Area V4: These cells give their strongest responses to frequency gratings; some V4 cells give even stronger responses to concentric and radial stimuli (pictured below); also has many cells that respond most strongly to color differences: Facial Recognition Regions: prefrontal cortex contains restricted region of neurons that are activated by faces; this indicates that pathway mediating visual recognition extends from V1 through temporal cortex to prefrontal cortex Area V5/MT: Also called medial temporal area or area MT; V5 neurons respond to moving visual stimuli (specialized for the perception of motion and its direction) Lesions of area V5 impairs performance of reporting direction of perceived motion; Electrically stimulating area of V5 causes you to report the wrong direction of motion (alters experience of visual motion) Damage to Area V5: after stroke damaged woman's area V5, she was unable to perceive continuous motion; only saw separate, successive still images (ex: could not read lips), but otherwise her visual perception was normal

"Depression and its Treatment" Video

Around 10% of people will at some point n their lives be affected by depressed Feeling sad, distressed, unmotivated, excessively tired, anxious, an decreased interest in activities Many brain circuits that normally regulated mood are dysregulated in depression; amygdala processes highly salient stimuli, but in depression, the amygdala is overactive and responds excessively to negative events The amygdala connects to set of brain regions that hone the physiological and behavioral response to emotional stimuli; these areas include the medial prefrontal cortex, the hippocampus, the nucleus accumbens and the insula The hippocampus is involved in memory formation, and is vulnerable to effects of stress Depressed people are more susceptible to stress, which can cause physical changes in the brain, including atrophy of the hippocampus; this, and other changes may cause inappropriate responses to emotional events The medial prefrontal cortex is involved in regulating how strongly we react to emotional stimuli; treatments such as antidepressant drugs, cognitive behavioral therapy, and electrical convulsive therapy affect the structure and function of these and other brain regions Mice subjected to chronic stress show some symptoms similar to depressed humans, such as anxiety like behavior, less social interaction, etc. While not all human depression is triggered by stress, these models may still shed light on the biology of depression and they're the closest scientists can get while studying mice Chronic stress in mice can lead to atrophy of the hippocampus and prefrontal cortex; mouse studies have shown altered neuronal plasticity in various brain regions including the hippocampus, prefrontal cortex, amygdala, and nucleus accumbens In a healthy hippocampus, experiences can lead to changes in the connections between neurons wrestling in learning these changes are referred to as plasticity; chronic stress can reduce this plasticity Healthy brains continue to produce new neurons in one part of the hippocampus; these new neurons slowly mature and integrate into the circuitry where they have a strong effect on hippocampal activity and behavior These new neurons are also affected by stress; they're reduced in number in stressed brains; these effects may result from reduced levels of neurotrophins proteins that increase neuronal growth and plasticity Reduced plasticity may stop hippocampus from being able to properly regulate the stress response, which may lead to a vicious cycle where stress perpetuates more stress; the hippocampus is particularly affected; but there can be reductions in plasticity elsewhere in the brain, and together, these changes could contribute to other symptoms of depression like anhedonia; Most antidepressants available today rapidly increase the amount of the neurotransmitters serotonin and/or norepinephrine in the synapse; however, improvements in symptoms in patients and mice usually don't occur until weeks after starting the treatment; while the reasons for this delay aren't fully understood, prolonged treatment with antidepressants can over time act to reverse some of the changes induced by chronic stress, increasing neurotrophin expression and rebooting hippocampal plasticity Non-chemical treatments for depression, including electroconvulsive shock, also promote hippocampal plasticity in mice Antidepressant treatment can also reverse stress-induced change in other areas of the brain, including the prefrontal cortex, and reward circuitry; different treatments may target different regions to improve symptoms Recently, the drug ketamine was found to have rapid antidepressant effects in patients with depression, as well as in rodent models with effects lasting for days; the mechanism behind this is an area of active research Ketamine block satype of synaptic transmission, leading to activation of a number of signaling pathways and increasing neurotrophin expression; these molecular changes result in increased plasticity in the prefrontal cortex and hippocampus and likely contribute to ketamine's behavioral effects

Patient H.M. and LTP

As H.M.'s amnesia may have been caused by loss of medial temporal lobe structures such as the hippocampus, this loss of the hippocampus translated to a loss of LTP to consolidate short-term memories into long-term memories

What Happens When You Remove the Hippocampus Video:

As a boy, HM cracked his skull in an accident Skoville decided to remove HM's hippocampus (based on the notion that mental functions were strictly localized to corresponding brain areas, and notion that he could reduce seizures) HM's seizures virtually disappeared, with no change in personality, but he was unable to form new memories Brenda Milner went to his house to study him; found that he still retained enough info to finish a sentence, but five minutes later, orgot test had taken place How Memories are Formed: After sensory data is transcribed by neurons in cortex, it travels to hippocampus, where special proteins work to strengthen the cortical synaptic connections; if the experience was strong enough or if we later recall it, the hippocampus then transfers the memory back to the cortex for permanent storage HM's mind could form the initial impressions, but without the hippocampus to perform memory consolidation, they eroded Milner discovered that declarative is different from procedural memory, which relies more on basal ganglia and cerebellum

Retina Projects to the Brain in a Topographic Fashion

As info travels from retina to brain, there's a point-to-point correspondence between neighboring parts of the visual space, which form a maplike projection of the components of the eye Most of this topographic projection consists of projection of the foveal region; V1 is located mainly on medial surface of cortex, and about half of V1 is devoted to fovea and retinal region around the fovea; This representation enables great acuity in the central part of visual field (another reason why vision is more acute in foveal region is because we devote proportionally more brain regions to analyzing info from that region)

Ganglion Cells

Cells in the retina that receive info from bipolar cells and whose axons form the optic nerve, which carries info to the brain

Scotopic and Photopic Systems Operating Simultaneously

At moderate levels of light, both rods and cones function, and some ganglion cells receive input from both types of receptors

Neurogenesis, Cell migration and Cell Differentiation (steps 1-3)

At three weeks, tissue layers have a clear fate and a purpose in the nervous system Ectoderm gives rise to neural plate, which gives rise to epidermis, external glands, hair, nails, anterior pituitary, which in turn gives rise to hormone regulation and homeostasis; in this layer, cells pinch off to become the neural tube Mesoderm gives rise to skeletal and smooth muscles, blood vessels, bone, and endocrine glands, heart, uterus, testicles, lymph, and blood cells Endoderm gives rise to colon, stomach, intestines, the lungs, the liver, pancreas Neural crest gives rise to meninges, PNS, enteric NS, melanocytes, facial cartilage, odontoblasts, neuroendocrine cells, spiral membrane (you don't want damage here) Neural tube gives rise to the CNS The forebrain, midbrain and hindbrain form within less than one month of gestation; the tissue has become those regions at about a month old embryonically

How energy Transmitted Through Air Becomes Sound

Auditory system detects changes in vibration of air molecules that are caused by sounds sources; Senses both intensity of sounds; measured in decibels (dB) --a measure of sound intensity, perceived as loudness and Their frequency, measured in hertz (Hz--cycles per second, as of an auditory stimulus), and perceived as pitch The outer ear directs sound into the inner parts of ear, where force of sound is transduced into neural activity (action potentials that infom brain); ears are very sensitive

Drug Treatments for Anxiety Disorders

Benzodiazepines Anxiolytics

Free Nerve Endings

Axon that terminates in the skin and has no specialized cell associated with it; these detect pain or itch, or changes in temperature All of the above skin sensory receptors are highest in concentration in regions of skin where our sense of touch is finest (fingertips, tongue, lips)

Sketch the interacting pathway of the neural systems underlying sleep: forebrain (reticular formation), brainstem, pontine system (locus coeruleus), hypothalamic system.

Basal Forebrain: generates Slow Wave Sleep Releases GABA into the tuberomammillary nucleus in the hypothalamus Stimulation of this region makes animals sleepy, Imposes SWS on the brain Lesions induce insomnia Brainstem: wakefulness Reticular formation region in the brainstem activates the forebrain Group of cells whose axons and dendrites course in many directions Stimulation promotes wakefulness and alertness and activates the forebrain Pushes brain from SWS into wakefulness Lesions in this region induce persistent sleep Pontine system: triggers REM sleep *locus coeruleus: nucleus in brainstem whose nucleus produces norephrine and modulates large areas of the forebrain Lesions of this area abolish REM sleep Stimulation prolongs REM sleep Prevents motor neurons from firing: inhibitory GABA and glycine produces inhibitory potentials in spinal motor neurons Muscles are flaccid, lost of muscle tone (body paralysis) Hypothalamic system: coordinating centre among these 3 other centres

Understand the changes in a neuron's membrane that produces a large electrical signal called an action potential.

Because Na+ is smaller than K+, it can also pass through the leaky channel At rest, there are more K+ ions inside the cells, more Na+ on outside, and the cell is more negative on the inside than on the outside Sodium potassium pump: active, pumping three Na+ in for two K+ out, which creates a net inside gain that's positive, and that changes the equilibrium potential, which is -65 mV Where does the voltage-gated sodium channel open? Sodium is entering the cell, this channel is sensitive to sodium changes, making the inside of the cell more positive, and thus they open at B, located before the peak; they help move the state of the neuron to an action potential; they open when membrane channel reaches about -55 mV, or threshold Resting potential: Sodium-potassium pump: pushing three Na+ in for two K+ out, creates a net inside gain that's negative; requires lots of energy Cell contains many large, negatively charged molecules such as proteins that don't cross membrane Membrane Permeability to Ions: Leaky K+ channels: membrane is only permeable to K+ ions, allows cell to reach equilibrium potential; departure of K+ ions leaves inside of cell more negative than outside, as Na+ cannot pass back inside K+ Equilibrium Potential: when enough K+ ions have departed to bring membrane potential to -65 mV, electrical attraction pulling K+ in is balanced by concentration gradient pushing K+ out; this is the K+ equilibrium potential (resting potential) More K+ on inside than on outside; concentration gradient wants them to go out, electrical gradient wants them to come in; More Na+ on outside than on inside; both concentration gradient and electrical gradient want them to go in Depolarization: decrease in membrane potential (Ex: depolarization of membrane potential from -65 mV to -50 mV brings inside closer to zero) Depolarizing pulses to membrane produce local graded responses, but situation changes if stimulus depolarizes axon to 40 mV (thresheld), after which the action potential is provokes; This is a reversal of membrane potential that makes inside of neuron positive with respect to outside Sodium-Potassium pump enforces the concentrations of ions taht maintain the resting potential

How Sensory Events Are Encoded As Streams of Action Potentials

Because action potentials produced by sensory neurons always have the same size and duration, intensity of sensory stimulus is encoded in the number and frequency of action potentials, their rhythms, etc. We respond to only small differences in stimulus intensity, over wide range of intensities Because neurons can fire only so fast, some sensory systems employ multiple sensory receptor cells (each specializing in one part of the overall range of intensities) to cover the whole range As strength of stimulus increases, additional sensory neurons sensitive to the higher intensities are 'recruited,' and thus, the intensity of stimulus can be represented by number and thresholds of activated cells

Aggression

Behavior intended to cause pain or harm to others (emotional or physical)

How Mood Cycles Between Extremes in Bipolar Disorder

Bipolar Disorder: characterized by periods of depression alternating with periods of excessively expansive mood (mania) that includes sustained overactivity, talkativeness, strange grandiosity, increased energy While some people exhibit rapid-cycling bipolar disorder (four or more distinct cycles in one year), some have longer or shorter cycles Men and women are equally affected by bipolar disorder; age of onset is earlier than that of depression; the disorder is evidently heritable People with bipolar disorder that enlarged ventricles (as in schizophrenia); the more amnif episodes person has experiences, the greater the ventricular enlargement Bipolar disorder has more in common with schizophrenia than with depression; extreme energy of people in manic phase may resemble delusions in people with schizophrenia Lithium: most people with bipolar disorder benefit from taking element lithium, a treatment discovered by accident

Molecular Mechanisms Involved in Detection of Bitter Tastes

Bitter tastes often signal presence of toxins; thus, we have evolved high sensitivity to different kinds of bitter tastes Members of the T2R family of receptor proteins (there are about 30 members) function as bitter receptors; Each bitter-sensing taste cell produces most of the different types of T2R bitter receptors, so bitter-sensing taste cells are sensitive to any bitter-tasting substances:

Facial expressions

Boil it down to six or seven to eight depending on who you ask There's so much variation based on the intensity of the emotion experienced

Analgesic Drugs

Brain-derived painkillers include endorphins and other endogenous opioids Opiate Drugs: most effective pharmacological method of pain control; opium-related drugs that relieve pain sensations; opiate drugs bind to specific receptors in brain to reduce pain This action is especially pronounced in brainstem region called the periaqueductal gray, possibly because brainstem system activates pain-gating mechanism of spinal cord via descending projections, thus blocking transmission of pain signals Epidural/Intrathecal Injection: relieving pain sensations by injecting opiates directly into the spinal cord Usually, people who are using painkillers to treat severe pain don't become addicted to them Naloxone (Narcan): an opioid antagonist that can save addicts' lives (blocks receptors for endogenous opioids) Over-the-Counter Pain Medications: Medications like aspirin and Tylenol act via non-opiate mechanisms to reduce pain and inflammation and cannabis reduces pain by stimulating endogenous cannabinoid receptors in spinal cord and brain

Embryo to Fetus

By end of eighth week, human embryo shows simple beginnings of most body organs; by this time, head is half size of embryo; during first ten weeks after fertilization, developing human is called embryo, and it's a fetus afterwards Six Distinct Stages of Nervous System Development: (1) Neurogenesis: mitotic division of nonneuronal cells to produce neurons (2) Cell Migration: massive movements of nerve cells or their precursors to establish distinct nerve cell populations (nuclei in CNS, layers of cerebral cortex etc.) (3) Cell Differentiation: the refining of cells into distinctive types of neurons or glial cells (4) Synaptogenesis: establishment of synaptic connections as axons and dendrites grow (5) Neuronal cell death: the selective death of many nerve cells (6) Synapse Rearrangement: loss of some synapses and development of others to refine synaptic connections, which extends throughout our lifespan

Structural and Functional Changes of Brains of Schizophrenics

CT and MRI scans reveal significant, consistent anatomical differences in brains of those with schizophrenia; these scans confirm that genes alone cannot account for whether person will develop schizophrenia Ventricular Abnormalities: Most people with schizophrenia have enlarged cerebral ventricles (especially lateral ventricles); these enlarged ventricles come at the expense of brain tissue; Twins with schizophrenia have decidedly enlarged lateral ventricle compared with their counterparts; those with larger ventricles benefit less from antipsychotic drugs:

Role of Neurotrophic Factors in Experience-Driven Synapse Rearrangement:

Ex: if postsynaptic cells are making limited supply of a neurotrophic factor, and if active synapses take up more of the factor than inactive synapses, then the inactive axons retract for lack of neurotrophic factor (ex: brain derived neurotrophic factor--BDNF--is a neurotrophic factor being competed for in the visual cortex)

Priming

Change in the way one processes a stimulus due to the fact that you've seen it previously; doesn't require declarative memory of the stimulus (ex: if person is shown the word "stamp" and later asked to completed the word STA-, they'll most likely say "stamp" as opposed to "start") Includes perceptual priming (based on visual form of words; associated with reduced activity in bilateral occipitotemporal cortex), conceptual priming (based on meaning of words; associated with reduced activation of left frontal cortex H.M. and people with amnesia have priming for words they don't recall seeing Priming involves the neocortex; NOT impaired by damage to the basal ganglia

The Dopamine Hypothesis

Chlorpromazine and other antipsychotic drugs for schizophrenia block postsynaptic dopamine receptors (particularly D2) receptors; because of this, research proposed the dopamine hypothesis; Dopamine Hypothesis: people with schizophrenia have either an excess of dopamine release or excess of dopamine receptors High doses of amphetamine cause excess of dopamine to accumulate in synapses, resulting in transient amphetamine psychosis that's similar to schizophrenia First-Generation Antipsychotics: all of the various drugs classified as these are D2 receptor antagonists; clinically effective dose of these can be predicted from their affinity for D2 receptors (ex: haloperidol has great affinity for D2 receptors and became widely used: Problems with this hypothesis is that there's no correspondence between speed with which drugs block dopamine receptors and how long it takes for symptoms to diminish (usually weeks) Developments of new drugs suggested that symptoms of schizophrenia respond to modifications of other neurotransmitter systems;; Second-Generation Antipsychotics (atypical antipsychotics): drugs that have only moderate affinity for D2 dopamine receptors; rather, they have highest affinity for other receptors; Ex: clozapine blocks serotonin receptors Second generation antipsychotics are just as effective as older generation of drugs for relieving symptoms of schizophrenia; evidence against dopamine hypothesis is that supplementing antipsychotic treatments with L-dopa, increasing dopaminergic activity, helps reduce symptoms of schizophrenia Second generation antipsychotics are less likely to cause side effects in motor function, but more likely to cause weight gain

Antipsychotic Medications for Schizophrenia

Chlorpromazine: drug that replaced lobotomy as treatment for schizophrenia; observations revealed that it could reduce positive symptoms of schizophrenia This reduced hallucinations, delusions, and disordered thinking, and relieved symptoms for many, revolutionizing treatment of schizophrenia However, sometimes people taking antipsychotics develop undesirable side effects in movement

Describe current perspectives and use of animals in research.

Class Notes/Lecture Material: Animal research policies require ethical practices Textbook Material: Minority of people believe ardently that research with animal is unethical, while others argue that's it's acceptable only when it produces immediate and measurable benefits Researchers have ethical obligation to hold pain and stress to minimum levels, and they are bound to constantly refine lab practices Researchers are subject to animal protection legislation and administrative oversight Because only some traits in tested animals are conserved in humans, it is incumbent upon researchers to determine how animals are identical and different; must ask: Does the proposed animal model really have some things in common with the process at work in humans? In studying something as complicated as the mammalian brain, there's often no choice but to study the brains of lab animals (majority rats and mice)

Understand what abnormal 'cultivation' of neural connections are and how they may underlie susceptibilities to neurological disorders.

Class Notes/Lecture Material: Astrocytes: detect neural activity and regulate adjacent capillaries to control blood flow, supplying neurons with more energy when they are active; these are very diverse; neurons wouldn't be very strong without them; they can also bugger extracellular ion concentrations, and can add and remove connections between neurons Compose 20% of the brain's cells Microglia: surround/engulf and break down any debris that forms, especially after damage to the brain Comprise 5-15% of the brain's cells Microglia in neurodevelopment: abnormal 'cultivation of neural connections could underlie susceptibility to neurological disorders Interested in how microglia are refining the dopamine synapses, which is mostly in the basal ganglia for motor control; was able to show that microglia have dopamine receptor inside of them; 30-day old rats: significant increase in the amount of dopamine that was in these microglia; But why do they do this, and what is directing it? Hypothesis: changes in dopamine activity (i.e. dopamine released into the synapse) can change what microglia are eating To answer this experimentally, they needed to functionally manipulate dopamine activity (can do this by directly turning on/off dopamine neurons; also have cell-type specificity; can also do this in live awake animals, but this can be invasive and unnatural/artificial) Textbook Material: Multiple sclerosis: disease in which myelin is compromised, with highly variable effects on brain function; here, the immune system generates antibodies that attack one or more molecules in myelin, which disrupts saltatory conduction Astrocytes and microglia may worsen Alzheimer's and Parkison's disease Neurons don't function very well without their glial cell neighbors Without microglia, you can have too many synapses, which could result in seizures; aberrant pruning could lead to autism and schizophrenia Factors in environment and person's genome could affect microgli's ability to find and destroy synapses, which could lead to schizophrenia or Aleimer's Amoeboid microglia are found in brains of autistic patients If microglia are kicked into overdrive, they act unruly Activated microglia and neuroinflammation are hallmarks of Alzheimer's disease and PArkison's amyotrophic lateral sclerosis (failure of microglia to clean up dying cells, debris, and proteins could contribute to inflammation); Overproduction of cytokines by microglia could contribute to AD; synapse loss happens in AD

Labeled lines

distinct and segregated populations of taste receptor cells encode each of the taste qualities -- when one is down, the others still work 6th one for fatty taste?

Describe the structural and functional differences AND similarities between microglia and astrocytes.

Distinguish between the central and peripheral nervous systems.

Class Notes/Lecture Material: Central nervous system Spinal cord Brain; Cerebral cortex: seat of complex cognition; consists of frontal, parietal, temporal, and occipital lobes Corpus callosum is the system through which hundreds of axons connect the right and left hemispheres Postcentral gyrus: strip of parietal cortex just posterior to central sulcus that receives somatosensory info from the entire body Precentral Gyrus: strip of frontal cortex, just in front of the central sulcus, that's crucial for motor control Forebrain, midbrain, hindbrain (cerebellum, pns, medula, brainstem = midbrain, pons, and medulla; tenchepjelon and diencephalon form the forebrain Brainstem corresponds to neural tube Peripheral nervous system Sympathetic: generally fight or flight (not always the rule, however; ex: when you see huge bag of chips, pupils dilated heart pumps, salivation, digestion stimulated) Parasympathetic: generally rest and digest Textbook Material: Peripheral Nervous System: Portion of the nervous system that includes all the nerves and neurons outside the brain and spinal cord; PNS consists of nerves (some motor nerves, which transmit info from the spinal cord and brain to muscles and glands, and some sensory nerves, which convey info to the CNS) PNS divided into two systems: Somatic Nervous System: consists of nerves that interconnect the brain and the major muscles and sensory systems of the body Main pathway through which brain controls movement and receives sensory info from the body and sensory organs of the head; Nerves that comprise somatic nervous system are either cranial nerves (twelve pairs of nerves which arise directly from the brain, not from the spinal cord, and pass through separate apertures in the skull) or spinal nerves Autonomic Nervous System: consists of nerves that connect primarily to the internal organs

Understand how the action potential travels along the length of an axon.

Class Notes/Lecture Material: Conduction velocity increases with myelination and axon diameter increases with myelination; three classes of myelination: A (Greatest) A-beta (some) C (none) Myelination in the nervous system began when you were an embryo; is a fatty rich substance created by glial cells; Sodium cannot enter anymore in the refractory Na+ channels after it has traveled down the axons Which channels are involved in the progression of an action potential along hte axon? Voltage-gated K+ channel, voltage-gated Na+ channel; NOT leaky potassium channel Textbook Material: Action potential is regenerated along the length of the axon, as one spike of depolarizing electrical activity strongly depolarizes the next adjacent axon segment; because adjacent axon segment is covered with voltage-gated Na+ channels, depolarization immediately creates new action potential, and regenerates, etc. Influx of Na+ ions depolarizes adjacent segment of axonal membrane, opening new gates for inward movement of Na+ ions Axon conducts action potential in only one direction, from axon hillock toward the axon terminals, leaving in its wake a stretch of refractory membrane;

Distinguish between the brain waves - alpha, beta, delta, K-complex, SWS - in the different stages of sleep and waking.

Class Notes/Lecture Material: During the waking cycle, there are beta and alpha waves; this is desynchronized electrical activity; you're paying attention to different things at different times (beta activity is 15-20 Hz, and alpha is 8-12 Hz) Describe the frequency and amplitude of each of these stages: Stage 1: alpha waves; no beta activity; shallow stage of sleep; waves of smaller amplitude and higher frequency Stage 2: huge spike, called the K-complex; there's an activity spike because the brain is trying to reign in all of the activity together so we can slow it down Stage 3: SWS: delta waves and amplitude is huge REM Sleep: will occur somewhere between waking and stage one; has vertex spikes that are unique to REM sleep

Describe Dr. Eric Kandel's experiment for studying learning in a neuronal circuit.

Class Notes/Lecture Material: HHMI BioInteractive Video: how neurons generate action potentials, the methods for measuring and recording a neuron's activity; Dr. Eric Kandel; reductionist approach showed that serotonin at the synapse could modulate the activity of the circuit. It increased the action potential! Dr Kandel discusses how applying serotonin to these neurons enhances the strength of the synaptic connections between them; serotonin could increase the action potential; i.e. before the serotonin, if it took fewer pulses, then with the serotonin, it took fewer Textbook/HW Material: Serotonin Strengthens Synapses: Kandel discusses how applying serotonin to these neurons enhances the strength of the synaptic connections between them See whether he could take a radical reductionist approach to measuring neuronal activity; By taking a single sensory neuron and a single motor neuron and putting them in a dish, with the sensory neuron on top forming connections with the motor neurons and the serotonergic cells, and if you stimulate the modulatory neurons, you will strengthen the connection between the sensory neuron and the motor neuron Can substitute a pipette for insertion of serotonin, and if pop on serotonin once, you get a transgen facilitation of synaptic strength; if you give 5 puffs of serotonin, you get a facilitation that can last over one day Serotonin modulation depends on protein synthesis; long term memory differs from short term memory in requiring the synthesis of new proteins, and trying to find if you can witness this at the level of connection between the sensory neuron and the motor neuron; Experimented with this by applying inhibitors of protein synthesis, and they found that it selectively blocked the long term formation of memories without affecting the formation of short term memories; He thereby reduced the learning process to monosynaptic connection consisting of two cells and a puff of pipette; found that serotonin depolarized the motor neuron Serotonin Enhances Synaptic Potential: Serotonin is a molecule that enhances synaptic activity; this can be seen by comparing the size of synaptic potentials before and after application of serotonin to the medium in which the cells are cultured; After serotonin application, the synaptic potential becomes markedly larger; when synaptic potentials are larger, fewer are needed to trigger an action potential

Spatial Memory

Cognitive Map: A mental representation of the relative spatial organization of objects and info (ex: mice form a cognitive map to help them solve a maze) Hippocampus is crucial for spatial learning, as it encodes spatial location using selective neurons called place cells; natural selection favors enlargement of the hippocampus to enhance spatial learning; cortex is also involved in spatial learning Place Cells: A neuron in the hippocampus that selectively fires when the animal is in a particular location; if animal moves to new environment, place cells indicate to hippocampus to remap new location

Explain the changes in channels and movement of ions that underlie the action potential.

Class Notes/Lecture Material: Leaky potassium channels are not the ones for restoring the equilibrium, the K+ potassium voltage-gated channels are Lamictal inhibits voltage-sensitive Na+ channels used to reduce seizures Voltage-gated Na+ channels open to produce the action potential Textbook Material: Action potential is created by movement of Na+ ions into the axon; at peak, action potential reaches about +40 mV, and concentration gradient is pushing Na+ ions into the cell, balanced by positive charge pushing them out, thus reaching equilibrium potential for Na+ Action potential involves rapid shift in membrane properties; switches from potassium-dependant resting state to primarily sodium-dependent active state; Shift happens through the actions of the voltage-gated Na+ channel; as its pore is gated, the gate is ordinarily closed, but if axon is depolarized enough to reach threshold levels, channel's shape changes, opening 'gate' to allow Na+ ions through into neuron At threshold, channel changes shape to open the pore; relatively few Na+ ions need to enter to change the membrane potential; K+ ions rapidly restore resting potential When axonal membrane depolarizes, if depolarization is below threshold, Na+ channels remain closed; but when depolarization reaches threshold, a few Na+ channels open at first, allowing a few to enter, then they depolarize membrane even further, opening more Na+ channels, and process progresses until barriers are removed and Na+ ions rush in Phase 1: Resting potential: K+ leaky channels are open to create the resting potential; voltage-gated Na+ channels are closed; gated K+ channel is closed; Phase 2: Action potential: Depolarizing forces bring the membrane potential closer to threshold, and at threshold, voltage-gated Na+ channels open, causing rapid change of polarity (the action potential) Phase 3: Absolute refractory period: At threshold, voltage-gated Na+ channels open, causing a rapid change of polarity (the action potential) Phase 4: Relative refractory period: Na+ channels automatically close agan; then at beginning of relative refractory period, gated K+ channels open, repolarizing and even hyperpolarizing the cell (afterpotential) Phase 5: Return to resting potential: all gated channels close; the cell returns to resting potential

Understand how neurons integrate information - spatial and temporal summation - from other neurons - to generate inhibitory or excitatory postsynaptic potentials

Class Notes/Lecture Material: Part of the action potential story involves many small local depolarizing potentials that push the neuron to passing the threshold to reach and action potential = EPSP There are a couple ways to sum presynaptic spikes so that you can have postsynaptic spikes; either spatial or temporal summation Each neuron may be connected to up to 10,000 other neurons The presynaptic neurons can either be excitatory or inhibitory; Main inhibitory neurotransmitter: GABA: makes chloride ion enter the neuron Textbook Material: Graded EPSPs and IPSPs spread passively over the postsynaptic neuron, decreasing in strength over time and distance; whether postsynaptic neuron fires depends on whether depolarization exceeding threshold reaches axon hillock Postsynaptic response moderated by number and distance: Note: If many EPSPs are received, axon may reach threshold and fire; if both EPSPs and IPSPs arrive at axon hillock they partially cancel each other Because postsynaptic potentials spread passively and dissipate, resulting sum is influenced by distance (Ex: EPSPs from axon hillock produce larger effect than will EPSPs farther away Dendrites also expand the receptive surface of neuron, increasing the amount of input neuron can handle; the farther out on a dendrite a potential occurs, the less effect it should have at the axon, as potential decreases in size as it passively spreads Spatial summation: summation of potentials originating from different physical locations across the cell body; only if overall sum of potentials (both EPSPs and IPSPs is sufficient to depolarize the cell at axon hillock will action potential be triggered; this often takes excitatory messages from many presynaptic neurons) Temporal summation: The summation of postsynaptic potentials that reach the axon hillock at different times; the closer in time the potentials occur, the greater the summation;

Describe how the branches of the autonomic nervous system relate to behavior and organ systems.

Class Notes/Lecture Material: Peripheral nervous system Sympathetic: generally fight or flight (not always the rule, however; ex: when you see huge bag of chips, pupils dilated heart pumps, salivation, digestion stimulated) Axons of the sympathetic nervous system exit from middle parts of spinal cord, travel a short distance, and then innervate the sympathetic ganglia; axons from sympathetic ganglia then spread throughout the body Sympathetic innervation prepare body for immediate action: blood pressure increases, pupils of eyes widen, heart quickens, etc, which comprise the fight-or-flight response Organs receive norepinephrine from sympathetic nerves Parasympathetic: generally rest and digest Generally helps body to relax, recuperate, and prepare for future action Nerves of parasympathetic system originate in the brainstem and in the sacral spinal cord; Parasympathetic nerves travel a longer distance than sympathetic nerves, before terminating in parasympathetic ganglia (clusters of neurons that are usually located close to the organs they serve) Organs receive acetylcholine from parasympathetic nerves (balance btw these systems determines the state of internal organs)

Review techniques for studying cellular structure and function of the brain, including optogenetics, histology/fluorescent imaging, EEG/ERP, brain imaging (functional: fMRI, PET; anatomical: CT, MRI), DREADDs. Be able to differentiate when they are used.

Class Notes/Lecture Material: Textbook Material: Histology: the study of the microscopic structure of tissues Histological/More Invasive: Nissl Stains: A dye which normally stains the cell bodies of neurons, especially methylene blue Golgi stains: A tissue stain that completely fills a small proportion of neurons with a dark, silver-based precipitate Autoradiography: A staining technique that shows the distribution of radioactive chemicals in tissues Immunohistochemistry: The use of antibodies to visualize the distribution of a particular protein in tissue In Situ Hybridization: A method for detecting particular RNA transcripts in tissue sections by providing a nucleotide probe that is complementary to, and will therefore hybridize with, the transcript of interest Tract Tracers: A type of histological stain that is taken up by neurons and transported over the routes of their axons, allowing the sources and targets of axons to be visualized Fluorescence imaging: stain for microglia (and other proteins), 3D imaging, and live (in wake animals; invasive) Less Invasive: Computerized Axial Tomography (CAT or CT scans): A noninvasive technique for examining brain structure through computer analysis of X-ray absorption at several positions around the head; you move an X-ray source in steps around the head, and detectors on opposite side of head measure the amount of X-ray radiation that is absorbed Medium-resolution images, useful for visualizing problems such as strokes, tumors, cortical shrinkage Magnetic Resonance Imaging (MRI): A noninvasive brain-imaging technology that uses magnetism and radio-frequency energy to create images of the gross structure of the living brain; person's brain head is placed in a powerful magnet that causes all the protons in the brain to line up in parallel Provides higher-resolution images than CT with fewer damaging effects Diffusion Tensor Imaging (DTI): A modified form of MRI in which the diffusion of water in a confined space is exploited to produce images of axonal fiber tracts Functional MRI (fMRI): Magnetic resonance imaging that detects changes in blood flow and therefore identifies regions of the brain that are particularly active during a given task; uses rapidly oscillating magnetic fields to detect regional changes in brain metabolism Can't resolve the fine cellular structure of brain, and it's not photographic, it's created by a computer using mathematical models Too slow to track rapid changes in activity of networks of neurons, but fMRI combined with conventional MRI has revealed how brain structures collaborate on complex cognitive processes Positron Emission Tomography (PET): Brain-imaging technology that tracks the metabolism of injected radioactive substances in the brain, in order to map brain activity; depicts brain's activity during behavioral tasks; PET can't match the detailed resolution of fMRI, but it's faster and better able to track changes in brain activity Transcranial Magnetic Stimulation: A noninvasive technique for examining brain function that applies strong magnetic fields to stimulate cortical neurons in order to identify discrete areas of the brain that are particularly active during specific behaviors Using this allows experimenters to map cortical surfaces by activating discrete areas of the brain, while simultaneously tracking any resulting changes in behavior Magnetoencephalography (MEG): A noninvasive brain-imaging technology that creates maps of brain activity during cognitive tasks by measuring tiny magnetic fields produced by active neurons Can track quick changes in brain activity; optimal for studying rapidly shifting patterns of brain activity in cortical circuits that fMRI is too slow to track Optogenetics = light + genes; a somatic, invasive intervention; **Selected neurons are genetically programmed to have an opsin ion channel in its membrane that responds to light. You know which neurons produce a behavior when stimulated naturally? Program those and induce the behavior with light! When light is shown on cell that have these channels, they open and allows positive ions to flow in the cell, depolarizing it and giving it higher chance of firing action potential Through light remote control, can activate or inhibit (ex: if there were a Cl- ion channel activiates, it would open and hyperpolarize) Have to factor in many things such as how many cells, which cells, the age of the animal Allows you to identify causal link between neural activation and behavior and function; Unlike EEG, this here is a single neuron manipulation; this is a reductionist approach to neural circuitry

Describe where the homunculus is found on the brain and what it represents. Discuss two criticisms of the homunculus.

Class Notes/Lecture Material: Textbook Material: Maps of how Criticisms of this model: it doesn't show overlapping regions and doesn't represent the female brain This "map" of how the various parts of the body are laid out on the cortex set a precedent; this revealed that brain function is organized in a map that reproduces body parts; this map is distorted (ex: body parts especially sensitive to touch comprise a larger area of cortex); This is the basis of what is called the 'homunculus,' drawn on surface of cortex to depict Penfield's maps

Differentiate the conduction velocity and action potential propagation along a myelinated versus unmyelinated axon.

Class Notes/Lecture Material: Textbook Material: Myelin is an electrical insulator; the conduction is continuous along the unmyelinated axon There is rapid saltatory conduction along the myelinated axon Conduction velocity varies with the diameter of the axon; larger axons = depolarization spreads faster Myelin sheathing (provided by glial cells) speeds up conduction; action potential "jumps" from node to node (saltatory conduction)

Describe how Dr. Wilder Penfield used electrical stimulation in his patients to generate a "map" of the brain.

Class Notes/Lecture Material: Wilder Penfield experiment: he thought that if he could provoke an aura with mild electrical currents, then he could locate the source of the seizure activity and then remove or destroy that bit of tissue He made a broader discovery that any place that he stimulated in the brain had a very specific response, so the brain was organized In the temporal lobe area, he found areas where, if he stimulated them, people had very specific memories This told him that there's a really organized way in which memories and experiences are stored He developed a map of the brain; the electrocorticography was the instrument he used to stimulate different parts of the brain Textbook Material: In an experiment which was meant to improve the success rate of seizure-removing surgeries, neurosurgeon Wilder Penfiled exposed his patients' brain to electrodes to provide electrical stimulation to surface of cortex when they were awake; tried to find point where stimulation recreated an aura In his work, he made monumental discoveries about the organization of the human cortex; by recording the effects of stimulating different regions of the brain, found that stimulation of these different regions caused patients to experience certain sensations; Through such studies, Penfiled discovered that each side of cortex receives info from and sends commands to opposite side of the body (ex: stimulating the postcentral gyrus of parietal cortex caused patients to experience certain sensations on parts of the body); **Each side of the brain receives sensory info from the opposite side of the body, organized along the postcentral gyrus of the parietal lobe; across the central sulcus, in the precentral gyrus, cortical regions control movement of that same part of the body so that sensory and motor regions are aligned This "map" of how the various parts of the body are laid out on the cortex set a precedent; this revealed that brain function is organized in a map that reproduces body parts; this map is distorted (ex: body parts especially sensitive to touch comprise a larger area of cortex)

Explain the role of cortisol, melatonin, caffeine, adenosine and dopamine on wakefulness and sleep.

Class Notes/Lecture: Cortisol: Regardless of your sleep experience, light triggers the release of cortisol and epinephrine Cortisol = wakefulness Caffeine: Caffeine binds to the adenosine receptor, blocking it from promoting sleepiness Caffeine inhibits adenosine action potential whether by locking it from binding, or it blocks the action potential impulse Dopamine: Dopamine enhances caffeine's action potentials, and promote more energetic alertness; dopamine is a caffeine modulator Adenosine: If adenosine binds to the receptor, then dopamine can't fit, so sleepiness takes over The pineal gland releases melatonin and that promotes sleep, and then it comes back to the SCN; Cellular timeline is an endogenous chemical, meaning that even if there's no light the system doesn't care

Describe what EEG measures and what distinguishes it from ERPs.

Class Notes/Lecture: It's not invasive, can pick up abnormalities, it's affordable Measurement for a long time Great temporal resolution; the temporal resolution for EEG is somewhere on the order of milliseconds, depending on the length of the axons; we are seeing, in real time, how the brain is reacting to our environment; fMRI brain imaging is limited, because it only measures blood flow to certain areas of the brain Event-Related Potentials (ERP): EEG responses to a single stimulus such as light or a sound; a specific stimulus that has a certain latency (time); this is the best use of ERPs

Describe and distinguish between the three types of research approaches: correlational studies, somatic intervention, and behavioral interventions.

Class Notes/Lecture: Textbook Material: Somatic Intervention: An approach to finding relations between body variables and behavioral variables that involves manipulating body structure or function and looking for resultant changes in behavior (i.e. we alter a structure or function of the brain or body to see how this alteration changes behavior); physical alteration = independent variable; behavioral effect = dependent variable Ex: administering a hormone to some animals, but not others, and comparing their sexual behavior; electrically stimulating a specific brain region and measuring alterations in movement; destroying a specific region in the brain and observing changes in sleeping patterns Behavioral Intervention: In this approach, scientist alters or controls the behavior of an organism and looks for resulting changes in body structure or function; behavior = independent variable; change in body = dependent variable Ex: allowing adults of each sex to interact and then measuring their hormone levels; having a person perform a cognitive task while in a brain scanner and then measuring changes in specific regions of the brain; training an animal to fear a previously neutral stimulus and then observing electrical changes in the brain that encode the newly learned association Correlational Studies: Measure how closely changes in one variable are associated with changes in another variable; Ex: observing the extent to which memory ability is associated with the size of a certain brain structure; noting that increases in a certain hormone are accompanied by increases in aggressive behavior Note: these studies can't establish causality, but can help researchers identify things that are linked

Understand the contributions that key early figures made to the field, and modern-day figures, including Ramón y Cajal, Penfield, and Kandel.

Class Notes/Lectures: Aristotle had an observation that a chicken could live without its head but not its heart (1945); believed that the spinal cord and brain stem were spared and that their was a blood clot (called him "Mike" the headless chicken); they fed him with an eye-dropper They're the ones that brought on the more brain-centered view They said not only the frontal region of the brain was linked to a judgment, but sensation and perception, and that there were fluid-filled cavities called ventricles Galen - he dissected animals and developed anatomical ideas that were shared in all medical schools; he continued to explore how the spinal cord innervates; also had access to gladiators, who suffered many brain injuries Decartes - explained that animals are like machines, have autonomic responses; but also recognised that we have free will and that we can make decisions that have something to do with our environment; there's a dualism, in which there's a body, and there's a mind The first attempts at theories of brain localization began with phrenology; Gall - was fascinated by the physical characteristics of the body, and he was a skilled anatomist; he saw that there were traits determined by the brain's size; to some extent, we kind of agree with that today (ex: big forebrain that has 40 years worth of memories) However, was erroneous in that he thought the brain size was connected to skull size We can credit Gall for making the connection between anatomy and function There was a British psychologist who founded the British society of phrenology Flourens - born in 1794, simulated parts of brain using electricity of the parts of the brain that Gall has documented; also did some post-mortem studies Broca - British described that Broca's area as key to language expression Wernicke - concerned with understanding language Ramon y Cajal; one of the first to describe and draw glia Dr. Eric Kandel; reductionist approach showed that serotonin at the synapse could modulate the activity of the circuit. It increased the action potential; Dr Kandel discusses how applying serotonin to these neurons enhances the strength of the synaptic connections between them; serotonin could increase the action potential; i.e. before the serotonin, if it took fewer pulses, then with the serotonin, it took fewer

How the Cochlea Converts Vibrational Energy into Neural Activity

Cochlea: part of inner ear that converts vibrations from sound into neural activity is the coiled, fluid-filled cochlea; it's a spiral of three canals: Scala Vestibuli (Vestibular Canal): Scala Media (Middle Canal): Scala Tympani (Tympanic Canal):

Six Main Findings of Environmental Enrichment Study:

Compared with IC animals, EC animals have heavier, thicker cortex (especially in somatosensory and visual cortical areas) EC animals have enhanced cholinergic activity throughout the cortex EC animals have more dendritic branches on cortical neurons and more dendritic spines on those branches EC animals have larger cortical synapses (consistent with storage of LTM in cortical areas via changes in synapses and circuits) EC animals have more neurons in the hippocampus because newly generated neurons live longer EC animals show enhanced recovery from brain damage

Results

Comparing full vs. interrupted videos; average n During this test on Day 3, participants had more false memories for videos that had been interrupted during the reactivation on day 2 Brain Activity After Events: Looking at the aftermath of surprise; the plus sign allowed to perfectly control for visual input; They modeled each video offset, measured brain activity during fixation, and took a snapshot of the brain every 1 sec What happens in the brain after each video ends? Compare expected and surprising video endings

Patient SM

Complete bilateral amygdala damage; IQ in low-average range; HS education; some non verbal memory impairment but otherwise was dexterous Drawings of facial expressions from memory; insisted that she didn't know how to draw an afraid face, because she didn't know what it looks like. Produced only after repeated prompting and she was not satisfied with it. SM does not use information about the eyes or other info that the controls use in either emotion but is able to use info about the mouth normally

What is the purpose of the eye?

Consider all of its parts: Collects and focuses light onto the retina; some of us don't focus it very well, for example, if you're myopic Accommodation by lens, cornea and ciliary muscles (these are like all other muscles, can exercise them by doing smooth pursuit--following something as it changes its movement across your visual field--and practice looking at things from further away; it's not possible) Photoreceptors translate light to electrical-chemical signals: vitamin A (ex: can find it in carrots, leafy greens; the body converts beta-carotene to vitamin A; if you don't have enough of it, your cornea can disintegrate; Approximately 20% of the receptors on your cornea are pain receptors At the back of your eye, there are some retinal ganglion cells, and a small subset of them are light-sensitive (contain melanopsin, which means they don't mean any external stimuli to be light-sensitive) RGCs: subset of ganglion cells that are intrinsically photosensitive Retinal ganglion cells send info to the rest of the brain

Hippocampal formation

Consists of two interlocking C-shaped structures: the hippocampus itself and the dentate gyrus; at least three different pathways in the hippocampal formation display LTP (seen in some other brain regions too)

Patient H.M.:

Could carry on a brief conversation without being interrupted, could use short term memory (could repeat list of numbers immediately after they were given), but not long-term memory (upon being given a list of words and distracted by another task, then later tested on them, he could not repeat the list or even recall that there was a list) Henry's case provided evidence that short-term memory differs from long-term memory;

What is hippocampus doing

Create anatomical mouse and extract the average activation in the hipp Looking at correlation; hippocampal activation can have opposing effects on subsequent memory: After full videos, the hippocampus protects the memory from distortion After interrupted videos, the hippocampus changes the memory This suggests that the same amount of hippocampal activation can lead to opposite effects on memory

How Sleep Characteristics Change in Affective Disorders

Difficulty falling asleep and inability to maintain sleep are common in depression; Depressed people have significant reduction in stage 3 (slow wave sleep) and corresponding increase in stages 1 and 2 sleep; People with depression enter rapid-eye-movement sleep (REM sleep) much sooner after sleep onset than controls; * length of time before REM sleep begins correlates with severity of depression; moreover, they have increased amount of REM sleep during first half:

Long-Term Memory:

Declarative Memory Episodic Memory (hippocampus, medial temporal lobe, neocortex) Semantic Memory (medial and anterior temporal lobe, neocortex); ex: learning facts for class Nondeclarative Memory Procedural memory (basal ganglia, motor cortex, cerebellum); ex: riding a bike Priming and perceptual learning (neocortex, sensory cortex); ex: prison goggles result in miscalibration of motor cortex, but after several weeks, the person adapts to this, their brain learns to compensate and they get faster and more accurate at doing these tasks Classical Conditioning (form of associative learning, associated with cerebellum, amygdala and reward regions--VTA, NAcc) (ex: Dr Ng. automatically salivates when she sees her favorite pile of potato chips, this is an example of nondeclarative memory

*Be able to describe how Bekesky discovered frequency tuning in the basilar membrane of the Organ Corti;

Depending on type of sound wave, and how much frequency there is, it's going to make the basilar membrane curl out more or less (displacement) At the base, there's more flexibility and floppiness, and thus takes high frequencies best

Learning Objectives

Describe soundaves and how the ear's external and internal structures respond Distinguish between types of hearing loss and discuss deaf culture perspectives Illustrate the cochlea and how it converts into neural signals and its pathway Explain the principal features of sound that the NS uses for sound localization Discuss the auditory, gustatory, and olfactory system, from an ecological perspective. Describe the structure, function and distribution of the papillae on the tongue Describe 5 major tastes, their cellular mechanisms (receptor types), and a possible 6th Trace the pathway of the gustatory system to the brainstem and cortex Describe the main structures and functions from the olfactory receptors to the cortex Locate the vomeronasal organ and contrast pheromones from odorants. Discuss examples of plasticity, e.g. supertasters, BrainPort, parosmia, synesthesia Describe the purpose and guidelines of smell training

Learning Objectives

Describe the main theories of the relationship between emotion and physiological changes Discuss the integration of autonomic responses with the perception of specific emotions Review evidence for a core set of emotions and their role in guiding pre programmed responses to environmental challenges Discuss the role of facial expressions of emotion, cultural influences and neural pathways Describe tools that measure or may impact emotional states, including polygraph, massage, breathing methods Sketch and describe the process of fear conditioning, its neural mechanisms underlying fear and pathological states Discuss the research on testosterone and aggression in humans and other animals Describe the communication between the nervous system, immune system and brain responses to stress and impact on health

Learning Objectives

Describe the most common symptoms and characteristics of schizophrenia disorder Discuss the influences of both genes and the environment on risk for schizophrenia and mood disorders Describe several structural brain differences that manifest in people with schizophrenia Compare the mechanisms of action for several classes of antipsychotic drugs Evaluate the evidence for the dopamine and glutamate hypothesis of schizophrenia Recognize the major symptoms of depression, warning signs of suicide and resources fo info and help Compare the treatments for depression; bipolar disorder; and anxiety disorders Discuss the prevalence of mood disorders and contributory factors for demographic differences Describe the symptoms of the main anxiety disorders and their risk factors Describe several treatments for OCD, including brain surgery and stimulation Describe PTSD and the hypothesis that the disorder is a special case for fear conditioning Research approaches for uncovering biological bases to psychopathology at all levels of analyses; if you want to look at social interactions and environment, etc, Social interactions with others and environment; Can self-report, make observations Family studies; adoption, twin studies; we know that developing brain is dynamic and there are epigenetic factors (ex: in bipolar disorder, ventricles are larger with time, and goes with more extreme episodes, so 65 is going to be very different than 21) Functional and structural brain developmental features Brain region responses to tasks (ex: Wisconsin sorting tasks); look at regions such as amygdala, hippocampus, etc. Drug effects on the circuit, cellular, synaptic and molecular levels

Neurosystem and plasticity

Developmental neuroscience involves organ-level, brain region, social level, brain region, circuit, cellular level, etc. Our nervous system is designed to be plastic; meant to take sensory stimuli in our environment The idea is that two of us will have similar types of neural equipment, but the similarity is that we have the ability to shape it, and because we have different experiences, languages, etc, we want a plastic neural system; early on, it's going to be much more plastic; over time, you will lose some plasticity (when you're an infant, your brain has to be very plastic because of one-trial learning, so it can learn how to coordinate sensory info, for example in breast feeding) There's a really important physiological cognitive stage at 18, 19, and 20 years of age; by the time you're 25, the plasticity is completely different than when you were 18 Neuromodulators such as acetylcholine and epinephrine are crucial to the development of the nervous system (need to activate certain neurochemicals in body); we also have the knowledge to unlearn something

Distinguish between invasive and noninvasive techniques.

Different design approaches can be used across the level of analysis and research tools can be invasive or non-invasive Textbook Material: Methods of studying the detailed structure and function of the nervous system vary in terms of their invasiveness Invasive techniques: in order to study the brain at the cellular level, often need to work with tissue samples or biopsies; often used in histology, the study of the composition of body tissues Non-invasive techniques: larger-scale activity of the brain can be studied using less-invasive functional imaging technologies

Major Depressive Disorder (MDD)

Different manifestations acrossculture, race/ethnicity, sex: Chinese: will manifest to clinicians by saying that they have bodily discomfort, dizziness Blacks: report feeling restless, insomnia Females: lose appetite, abnormal amount of weight change Males: erectile dysfunction, digestive problems Inequitable treatment across demographics Economic burden in 2010: $210.5 billion 45% direct costs, 5% suicide-related, 50% workplace

Key Objectives

Discuss the values and purpose for learning about memory Distinguish between categories of memory and their subtypes Describes studies that reveal brain regions and circuits underlying memory Describe studies that show and how memory can be influenced Describe some "memory hacks" to improve your study habits Discuss how surprising events affect the hippocampus and memory outcomes Describe the structure and psychological changes from synaptic plasticity Identify pathways in the hippocampus that support LTP Distinguish between habituation, differentiation, and learning Outline the steps in long-term potentiation Describe evidence that supports a biological bases for learning and memory One application of learning and memory includes drugs and addiction; alcoholic beverages are used the most by adolescents, followed by tobacco or nicotine delivery products

Cocaine on the brain

Disrupts normal synaptic transmission Acts as indirect dopamine agonist; inhibits reuptake of dopamine, more is hanging around, which will affect the EPSP Increases EPSP downstream (postsynaptic neuron) Regular use causes long term potentiation: psychological and structural changes at the synapse Tolerance may develop so that higher doses and increased frequencies may be both needed; this is result of synaptic changes; the biological basis of tolerance is LTP Animal research suggests that binging on cocaine during adolescence affects your behavior and interaction with it later in life; much more likely to use it later

What We Learned from HM:

Distinction between short term and long term memory; Distinction between procedural and declarative memory Retrieving old memories and encoding new memories Hippocampus = "seahorse" in Latin

Key Objectives:

Distinguish btw neuroplasticity and neurogenesis Explain the relationship btw experience, sensitive period, synaptogenesis and synaptic pruning Compare the techniques and evidence for observing adult neurogenesis in rodents vs humans Describe the 6 stages of cellular nervous system development, how they are interdependent, and problems when development goes awry Describe the structure and functional fates of the 3 embryonic tissues layers -- ectoderm, mesoderm and endoderm Connect abnormal processes to neurodevelopmental conditions: fragile x, neural tube defects, ectodermal dysplasia, PKU, dementia and autism spectrum disorder Explain the variability of an individual due to genotype, phenotype and epigenetics

Discuss three arguments for diversity in STEM.

Diversity in Stem matters because (https://blogs.scientificamerican.com/voices/diversity-in-stem-what-it-is-and-why-it-matters/): 1. Diversity is critical to excellence 2. Lack of diversity represents a loss of talent 3. Enhancing diversity is key to long-term economic growth and global competitiveness Ex: Alzheimer's disease, neuroplasticity, adult neurogenesis, multiple factors, from genetic to social behavior

Experimental Question

Do surprising events lead to distortion/updating of episodic memories; if so, what's going on in the brain (focus on hippocampus) Experiment: Use fMRI with human subjects (n = 24); let's create some false memories and watch it happen in the brain

Using Retinotopic Mapping to Identify Brain Damage

Due to the orderly mapping of visual field in terms of the visual system, damage to parts of the visual system can be diagnosed from perceptual defects within the visual field Scotoma: A region of blindness within the visual fields, caused by injury to the visual pathway or brain; If we can identify the site of injury in visual pathway, can predict location of this perceptual gap, or scotoma, in the visual field Scotoma is a spot where nothing can be perceived; Blindsight: Paradoxical phenomenon whereby, within a scotoma, someone can't consciously perceive visual cues, but may still be able to make some visual discrimination Within a scotoma, person can't consciously perceive visual cues, but some visual properties in this region may still function; people with blindsight cannot see, but when asked to guess whether a stimulus is present, they are able to answer this correctly

Synapse Rearrangement in Visual Cortex:

During early development, synapses are rearranged in visual cortex; axons representing input from each eye compete for synaptic places; active, effective synapses predominate over inactive synapses (thus, if one eye is 'silenced,' synapses carrying info from that eye are retracted, while synapses driven by other eye are maintained; Effective synapses (those that successfully drive the postsynaptic cell) might grow stronger at the expense of ineffective synapses Hebbian Synapses: synapses that grow stronger or weaker depending on their effectiveness: Hubel and Wiesel's Surgical Experiment: Hubel and Wiesel surgically caused eyes to diverge in kittens, causing visual stimuli falling on misaligned eyes to no longer provide simultaneous, convergent input to cells of visual cortex

AMPA/NMDA Receptors During Normal, Low-Level Activity:

During normal, low-level activity, the release of glutamate at the synapse activates only the AMPA receptors, so EPSP is mediated entirely by these AMPA receptors; thus, only the AMPA receptors function in exciting the neuron The NMDA receptor can't respond to the glutamate because Mg2+ ions are blocking the NMDA receptor's Ca2+ ion channel, and thus, few Ca2+ ions can enter the neuron

Desperate Treatment Attempts for Schizophrenia

In 1930s, psychiatrists turned to lobotomy, surgical separation of portion of frontal lobes from rest of brain, as treatment for schizophrenia; While surgery made patients easier to handle, they weren't able to leave mental institutions

Long-Term Effects of Antipsychotic Drugs

Dyskinesia: Difficulty of distortion in voluntary movement; sometimes, this effect is a permanent side effect of antipsychotic drugs for schizophrenia Tardive Dyskinesia: Characterized by repetitive, involuntary movements especially involving face, mouth, lips, and tongue; incessant rolling movements and smacking of the lips; some people jow jerking movements of legs The underlying mechanisms for this condition may arise from chronic blocking of dopamine receptors, resulting in receptor supersensitivity Supersensitivity Psychosis: Moreover, sudden discontinuation of the drugs or lowering dosage results in sudden increase in positive symptoms of schizophrenia; This can often be reversed by administration of increased doses of dopamine receptor-blocking agents

Test That Distinguished His Non-Declarative from Declarative Long Term Memories:

Each day, he improved his skills on a mirror-tracing task (reading mirror-reversed text); while his performance was better than on the first day, demonstrating a certain type of long-term memory (non-declarative); however, he did not remember taking the test This test demonstrated that he had an issue forming new declarative memories; important distinction was not between motor and verbal material, but between declarative and nondeclarative memory

Individual Differences in the Stress Response

Early experience contributes to individual differences in stress responses (ex: rats that have been briefly handled by humans as pups are less susceptible to adult stress than are rats that have been left along as pups) Stress Immunization: Previously handled rats secrete lower adrenal steroid amounts in response to wide variety of adult stressors; this is called stress immunization, as a little stress early in life made animals more resilient to later stress However, more research showed the the pups benefited because their mothers comforted them after the stress; this stimulation from mother is crucial for the stress immunization effect; the offspring of mother rats that cared for them more were more resilient in their responses to adult stress than other rats were; *thus, immunizing benefit happened only if pups were promptly comforted after each stressful event If pups were deprived of mother for long periods, as adults they exhibit greater stress response and show reduced neurogenesis Role of Epigenetic Regulation in Stress Response: As evidenced by fact that maternal deprivation exerts negative effect on adult stress response by causing changes in expression of adrenal steroid receptors in brain, stress can cause long-lasting epigenetic change In humans, brains of suicide victims have revealed same epigenetic change in expression of adrenal steroid receptor, but only in those who had history of child abuse; This implies that early abuse epigenetically modified expression of the gene, making person less able to handle stress and susceptibility to psychiatric disturbances

How Brain Lesions Also Affect Emotions

Early in 20th century, dogs whose cortex had been removed respond to routine handling with sudden intense decorticate rage; this suggests that emotional behaviors must be organized at a subcortical level, and cerebral cortex normally inhibits rage responses Papez's Subcortical Circuit of Emotion: James Papez noted associations between emotional changes and specific sites of brain damage; these interconnected regions are now known as the limbic system Limbic System: includes the mammillary bodies of hypothalamus, anterior thalamus, the cingulate cortex, the hippocampus, the amygdala, and the fornix Support for limbic system model of emotion came from studies of monkeys after removal of their temporal lobes; their behavior changed dramatically, having an extraordinary taming effect Kluver-Bucy Syndrome: Condition, brought about by bilateral amygdala damage, characterized by dramatic emotional changes, including reduction in fear and anxiety; Animals that had been wild and fearful of humans before surgery became tame and showed neither fear nor aggression afterward; also exhibited strong oral tendencies As this type of behavior is seen in monkeys in which only the left and right amygdalas have been destroyed, this suggests that amygdala is key structure in behavior changes of Kluver-Bucy syndrome, especially loss of fear

7 Neurons at Different Levels of the Visual System Have Very Different Receptive Fields

Examples of receptive fields of brain cells: lateral geniculate cell with concentric field; on-center/off-surround A simple cortical cell is sensitive to orientation; this particular cell responds strongly when the stimulus is a vertical stripe; A complex cortical cell is also sensitive to motion; this particular cell responds strongly only when the stimulus moves down; it responds weakly to upward motion and doesn't respond at all to sideways motion

Neural Tube:

Embryonic structure with subdivisions that correspond to future forebrain, midbrain, and hindbrain; as cell layers thicken, they grow to form groove that'll become the midline and then the neural groove; at the head end of this, thickened group of cells forms, and tops of neural groove come together to form neural tube The interior of neural tube becomes the fluid-filled ventricles of the brain, central canal of spinal cord, and passages that connect them The neural tube is the beginning of the central nervous system, and at the anterior part of neural tube, there are three subdivisions: Forebrain: Frontal division of neural tube; in mature vertebrate, contains the cerebral hemispheres (cortical regions), thalamus, and hypothalamus Midbrain: The middle division of the brain Hindbrain: The rear division of brain, which in mature vertebrate contains cerebellum, pons, and medulla

Three main phases of study:

Encoding phase: Goal: make a bunch of distinct memories so that we can mess with them later Stimuli: 70 unique narrative videos that feature action-outcome events Reactivation phase Goal: test the effect of surprising reminders of past experiences; Stimuli: The same 70 videos, but half were interrupted at a crucial moment (ex: right as batter was about to swing) Test Phase Goal: test for false memories, which show that a memory has been changed Format: structure interview recall test, cued with name of video:

Three Processes of the Memory System:

Encoding: First process in memory system in which the info entering sensory channels is passed into short-term memory; encoding of raw info from sensory channels into STM Consolidation: Second process in memory system n which info in short-term memory is transferred to long-term memory; Consolidation of the volatile STM into more-durable LTM Retrieval: Third process of memory system in which stored memory is used by an organism; retrieval of the stored info from LTM for use in working memory At any stage of the process, info may be forgotten Additionally, emotional arousal during an event can give our memories more traction

From Sensory Receptors to Action Potentials

End product of sensory receptors (action potentials) is same for all different sensory modalities, but brain recognizes these modalities as separate and distinct, because action potentials for each sense are carried in separate nerve tracts

Enrichment:

Enriched mice (social mice) have a heavier, thicker cortex Their cortex has more cholinergic (ACh) activity; those are the circuits that release acetylcholine More dendrites and dendritic spines Larger cortical synapses (more room for receptors to bind) More neurogenesis in the dentate gyrus of the hippocampus More memories recovered after brain damage in enriched mice

Epinephrine and Memory Formation:

Epinephrine is adrenaline released from adrenal glands during times of stress and strong emotion, and it affects memory formation by influencing the amygdala (which is a region involved in fear conditioning); Electrical stimulation or lesions of amygdala alter memory-enhancing effects of epinephrine injections; Small doses of epinephrine injected directly into amygdala enhance memory formation; this causes release of norepinephrine within the amygdala (as emotional experiences do) PTSD and Epinephrine Treatment: A strategy to prevent PTSD formation could be to treat victims with antiadrenergic drugs either immediately before or after an experience; this could diminish the traumatic aspects of a certain memory

Characteristics of OCD

Estimated that 1% of adults in US have severe OCD symptoms; Often, initial symptoms appear in childhood (however, peak age of onset is 25-44 years) OCD patients display increased metabolic rates in orbitofrontal cortex, cingulate cortex, and caudate nuclei Treatment for OCD: OCD shows excellent response to CBT and to several drugs; effective OCD drugs share ability to inhibit reuptake of serotonin at serotonergic synapses; suggests that dysfunction of serotonergic neurotransmission plays central role in OCD fMRI studies suggest that SSRI drugs alter activity of orbitofrontal prefrontal cortex in people with OCD, while primarily affecting ventrolateral prefrontal cortex in people with depression There is heritable genetic component to OCD; OCD can also be triggered by infections; children make antibodies that attack their own brains Psychosurgery may be treatment of last resort for OCD; ⅓ of people who underwent cingulotomy (making lesions that interrupt pathways in cingulate cortex) benefitted:

Inefficacy of Polygraph Tests

Estimated to have an overall efficacy of about 65%; is ineffective because can implicate people who are just nervous truth-tellers or those who are calm-liers Additionally, attempts to use brain scanners as lie detectors so far have yielded unreliable results

How Invertebrate Nervous System Studies Show Synaptic Plasticity Across the Animal Kingdom:

Even species that are only remotely related share the same basic cellular process for info storage One research strategy is focusing on memory mechanisms in the simple nervous systems of invertebrates; these systems have relatively few neurons, and they are arranged identically in different individuals, making it possible to create neural circuit diagrams for behaviors Habituation Study in Aplysia (Sea Slug): Scientists studied habituation in aplysia by squirting water at the slugs' siphon (tube through which it draws water), which normally causes the animal to protectively retract its gill; However, with repeated stimulation the animal retracts the gill less and less, as it learns that the stimulus does not represent danger to the gill **Eric Kandel determined that this short-term habituation is caused by changes in the synapse between sensory cell that detects squirt of water and the motor neuron that retracts the gill; in the case of Aplysia, this short term habituation results because the sensory neurons release less transmitter Additionally, the number and size of synapses can vary in training Aplysia (ex: if habituation test is performed over a series of days, each day, the animal habituates faster than it did the day before), which represents long-term habitation, in which there's a reduction in the number of synapses between the sensory cell and the motor neuron, or a retraction of some synaptic terminals **In general this demonstrates that learning can happen either through reduction/increase in strength of existing synapses (short-term habituation), or through reduction in number of synapses (long-term habituation)

Why does this research matter? Implications?

Eyewitness testimony: change our interview and courtroom practices to prevent memory distortion Learning and education: encourage students to generate predictions, retrieve info from memory, give good feedback Belief Updating: eliciting surprise may help us correct misinformation and update beliefs about the world Pathological memories: if we know how to change memories, we can reduce the impact of traumatic memories

Neurons in the Retina and LGN Have Concentric Receptive Fields

In addition to on- or off-center portions of bipolar and ganglion cells, their receptive fields have a ring around that center (called a "surround"), and thus the receptive field of bipolar cell is concentric; Photoreceptors in central area and those in surrounding ring have opposite effects on next cells in the circuit;

Retrograde Amnesia

Loss of memories that formed prior to an event (e.g. surgery or trauma); ranges from forgetting events that happened a few hours or days before the accident or even to a year before ("complete" memory loss is unlikely)

How Facial Expressions are Mediated By Muscles, Cranial Nerves, and CNS Pathways

Facial muscles can be divided into two categories: Superficial facial muscles: which mostly attach only between different points of facial skin, so when they contract, they change the shape of the mouth, eyes or nose, or create dimple Deep Facial Muscles: attach to bone and produce larger-scale movements, like chewing Facial muscles are innervated by two cranial nerves: Facial nerve (VII), which innervates the superficial muscles of facial expression; and Motor branch of the trigeminal nerve (V), which innervates muscles that move the jaw Activity of cranial nerves is governed by face area of motor cortex, which is a disproportionately large brain region in humans, reflecting importance of emotional expression

Declarative Memory

Facts and info acquired through learning; memory we are aware of accessing; tests of declarative memory usually request specific info learned previously (was severely impaired in H.M.) Can be tested readily in humans because of our ability to talk

Two Variables that Confound Correlations Between Testosterone and Aggression

Firstly, experience can affect testosterone levels (ex: in animals, loser in aggressive encounters shows reduced androgen levels; thus levels of testosterone sometimes are result instead of cause of behavior) In men, testosterone levels rise in winner and fall in losers after various competitions Second confounding variable is dominance; testosterone levels are often associated with behaviors that confer or protect the individual's social status This type of aggression is proactive: part of an offense strategy to improve individual's standing In contrast, reactive aggression encompasses defensive behavior that protects against external threats While lowered testosterone may reduce violence in some sex offenders, the main effect is reduction in sexual motivation more than direct effect on aggression

How the Brain Changes with Depression

Function changes detected by PET and fMRI reveal that, compared to control individuals, those with depression have increased activation in amygdala during emotional processing, increased activity in frontal lobes during cognitively demanding tasks, and decreased activity in parietal and posterior temporal cortex in the anterior cingulate cortex (systems implicated in attention) Descendants of those with severe depression have thinner cortex across large portions of right hemisphere Additionally, depressed people have difficulty regulating stress hormone release Many studies report hippocampal volume is reduced in those with depression, along with reduced activation of the hippocampal region in depressed people during memory tasks

Four Views on the Relationship Between Emotions and the Autonomic Nervous System

Folk psychology: my hands were shaking James-Lange Theory: the heart races, and then you experience the emotion of fear (not really thin Cannon-Bard Theory: heart races and at the same time I experience fear (these are happening independently but in parallel) Schachter-Singer Theory: the heart races, then let's think about the situation, then think "ok that's fear I'm feeling because I'm in grocery store and that shouldn't be happening"

Identify the major parts of a neuron and distinguish between the three structural types.

Four principal divisions of neuron: Input Zone: Neurons receive info via synapses from other neurons; receive these at their dendrites (more elaborately branched = more room for synapses); dendrites may be covered in dendritic spines, providing additional space for synapses Integration zone: neuron's cell body integrates (combines) the info that has been received to decide/determine whether or not to fire an action potential Conduction Zone: A single extension, or the axon, which carries the neuron's electrical signals away from the cell body; towards the end, axon may split into multiple branches called the axon collaterals Output Zone: specialized swellings at the ends of the zon, called amazon terminals, transmit the neuron's signals across synapses to other cells

Four Mechanosensory Neurons

Free nerve endings Merkel cells: use A-beta nerves to detect indentation and tactile stimuli to reconstruct spatial images; located in skin areas with high tactile acuity, e.g., fingertips, touch domes (highly sensitive area of hairy skin) Ruffini endings: are deep and have fluid-filled capsule space as the inner core; they sense skin stretch by interacting with collagen fibers Meissner corpuscles: use A-beta to detect skin's rapid movement and to control grip (fingertips and soles of the feet); enmeshed in connective tissue and are four times more sensitive than Merkel cells but lack ability tod determine spatial differences Vibration and pressure opens Na+ channels in Pacinian corpuscles; Strong stimulus opens Na+ channels and produces a graded generator action potential; it's graded because it cares about grade of stimulus A-beta nerve ending and cover large areas of skin to help manipulate objects

Fragile X Syndrome:

Frequent cause of inherited intellectual disability produced by a fragile site on the X chromosome that seems prone to breaking because the DNA there is unstable; this syndrome indicates that the selective loss of synapses via synapse rearrangement helps the brain function better Person with this condition has modified facial appearance, elongation of face, ears, and chin Cognitive Effects of Fragile X Syndrome: cortical neurons from brain possess an excess of small, immature dendritic spines; thus, syndrome affects mental development by blocking normal elimination of synapses after birth

Primary Auditory Cortex (A1)

Many sounds activate the primary auditory cortex, located on upper surface of temporal lobes While pure tones or noise activate chiefly the primary auditory area of the temporal lobe, speech sounds activate other auditory cortical regions, as well as the primary auditory area Auditory cortex integrates other, non auditory info with sounds Listening to words not only activates several regions of cerebral cortex,; also activates regions of thalamus and cerebellum

Inheritance is Important Determinant of Depression

Genetic studies of depressive disorders reveal strong hereditary contributions; concordance rate for identical twins (40%) is higher than for fraternal twins (20%) Research has failed to identify any particular gene associated with depression; many genes contribute to making a person more or less susceptible

Substances that activate the TRP channel and drugs that block them

Globulin and protein kinases: released by damaged tissue; the most active pain-producing substances Arachidonic acid (ex: aspirin): released during tissue damage, then metabolized into prostaglandin (and cytokines); prostaglandins block the K+ released from nociceptors following damage, which results in additional depolarization, and then nociceptors are more sensitive Histamine: tissue damage stimulates mast cells to release histamine to the surrounding area; histamine excites the nociceptors (Benadryl) Substance P (SP) and calcitonin gene-related peptide (CGRP): release triggered by injury and inflammation; this excites nociceptors; both peptides produce vasodilation, which results in the spread of edema around the initial damage (steroids, opioids) Potassium - K+: most tissue damage results in an increase in extracellular K+; there is a good correlation between pain intensity and local K+ concentration Serotonin (5-HT): acetylcholine, low pJ, (acidic) solution, and ATP; release is triggered by tissue damage Muscle Spasm and Lactic Acid: headaches can result from muscle spasms of smooth muscle and stretching (Ruffini) of a ligament. Blood flows to hyperactive muscle is blocked; lactic acid increases; leads to pain; lactic acid excites nociceptors

How Taste Info is Transmitter to Several Parts of the Brain

Gustatory System: taste projections of gustatory system extend from tongue to several brainstem nuclei, then to thalamus, and finally to gustatory regions of somatosensory cortex Labeled-Line Taste System: brain simply monitors which specific axons are active in order to determine which tastes are present Experimental evidence supports idea that taste is a labeled-line system; inactivating taste cells that express receptors for one of five tastes eradicates sensitivity to that one taste:

Opioid Crisis

HHS announced 5 priorities for addressing the opioid crisis: Improving access to treatment and recovery services Promoting use of overdose-reversing drugs Strengthening our understanding of the epidemic through better public health surveillance Providing support for cutting-edge research on pain and addiction Advancing better practices for pain management OTC pharmaceutical online sales growth in US in 2020: online sales for pain relief increased 164% in 2020

Nonassociative Learning:

Habituation: A decrease in response to a stimulus as it is repeated; here, decreased response can't be due to failure of sensory system to detect the stimulus or inability of motor system to respond, but due to habituation to the stimulus

Eric Kandel's Findings:

Habituation: decreased response to a stimulus (siphon squirting water) as it is repeated His reductionist animal of choice was the Aplysia; time matters in studying memory and habituation Short term habituation: the aplysia is going to withdraw its gills; if you do this over a while, that's long term habituation

Scala Media (Middle Canal):

Hair Cells: Receptor cells for hearing in the cochlea, named for the stereocilia that protrude from the top of the cell and transduce vibrational energy in the cochlea into neural activity; hair cells bridge between the basilar membrane and the overlying tectorial membrane Basilar Membrane: A membrane in the cochlea that contains the principal structures involved in auditory transduction; membrane Tectorial membrane: A gelatinous membrane located atop the organ of Corti; elaborate framework of supporting cells and auditory nerve terminals that transmit nerve signals to and from the brain

Cochlea > spiral ganglion> brainstem > superior olive > inferior colliculus > medial geniculate > auditory cortex

Hair cells: we have 17,500-23,500 Auditory nerve fibers from cochlea to cochlear nucleus: 30,000-50,000 We can understand different types of hearing loss now, and knowing that helps if the individual wants some attention for this (ex: damage to auditory brain structure can be caused by stroke or traumatic brain injury) In middle, sensorineural deafness is attributable to problem with the cochlea In 2019: worldwide 736,900 cochlear implants; US 118,00 in adults and 65,000 in children

**How and where are our memories stored?

Have good evidence of it being stored in neurons, synapses, circuits, etc One memory per neuron is not enough; (more like circuits); like space in an iPod, it's a few gigabytes 1 billion neurons x 1000 connections = 1 trillion connections per memory; that's one million gigabytes 1 million gigabyte = 3 million hours of Tv shows or 5000 years of MP3 songs What is a memory? Size, type, complexity, etc. We have common language to describe different types of memory; The more complex it is, more circuitry and broader brain regions involved How can you use this info to tap into your synaptic plasticity to optimize learning? Figuring out how to unlearn things that don't serve you 67,000 digits - student in China could remember this amount of digits in pi, and broke the world record; this is jamming your brain circuitry

Mike May:

He had corneal cell transplant in his left eye "The difference btw today and two years ago is that I can better guess at what I am seeing ...What is the same is that I am still guessing" His left eye was destroyed by chemical explosion, so for 43 years, he didn't have sight, but he had some light perception They asked if he wanted to do stem cell transplant to try to restore some of tissue in right eye (to reveal his retina so he could see) and he decided to undergo this transplant He responds to some stimuli (objects) There's a lot more activity in the control subject's brain vs. Mike's brain; there is more base activity around the fusiform gyrus, which tells us that the neural areas that are dedicated to faces in typical adults are going to be different than Mike's While controls have no difficulty distinguishing objects by sight alone, Mike May recognized objects less than 30% of the time before his surgery; When it comes to face processing, there was not much plasticity within those 43 years; however, the stimuli are not all equal; when you give him motion stimuli, he can see that just as well as normal subject; when he was blind, wasn't able to detect visual motion with accuracy

Damage to Medial Diencephalon Can Also Cause Loss of Ability to Form New Declarative Memories:

He had damage to various limbic system structures in the medial diencephalon that connect to hippocampus: the dorsomedial thalamus and the mamillary bodies: 1. dorsomedial thalamus 2. mammillary bodies

Dr. Purves

He studies music perception and consciousness: How bipolar cells and primary visual cortex respond to a particular illusion; (of the two indicated patches, the upper one looks darker, even though they are in fact the same shade of gray A lot of the primary visual cortex is dedicated to foveal vision, where a lot of the neurons are packed

Deafness

Hearing loss so profound that speech can't be perceived even with use of hearing aids; affects about 15% of population

Research Studies of Stress Response

Hormonal responses to stress were studied in group of young recruits in military; on each jump day, anterior pituitary released enhanced levels of hormones, and both sympathetic and parasympathetic systems were activated While initially cortisol levels were elevated before first jumps, they eventually returned to normal before jumps; Conversely, testosterone fell far below control levels on first day of training, but gradually returned to normal with subsequent jumps: Riding in commuter train provokes release of epinephrine, and longer and more crowded the ride is, the greater the hormonal response Stress of PhD oral exam causes dramatic increase in both epinephrine and norepinephrine; stressed students showed fMIR evidence of impairments in brain mechanisms controlling attention Sustained Social Stressors: ex: young people with asthma who experience stress due to peer rejection, etc. have more responsive adrenal system, more severe respiratory symptoms, and impaired expression of anti-inflammatory genes

How do we know that genes and non-genetic factors play a role in causing depression?

Heritability = roughly what percentage of their cause is due to genes; this is important to know because we want to know what the biological underpinnings are, have predictive info Method: Find people with disease who have twin Then ask: Is the twin monozygotic or dizygotic? Monozygotic = identical twins share 100% of their genes -- 76% Dizygotic = fraternal twins share 50% of their genes -- 19% Then ask: Does the twin have the disease? Monozygotic -- 86% to 76% Dizygotic -- 13 to 19% If genes are part of the cause, patients's identical twin has much higher risk of disease than a patient's non-identical twin Several functional and structural characteristics differ in psychopathology Dorsal prefrontal cortex image -- there's more activation patterns happening in controls than people with schizophrenia (referred to has hypofrontality -- decreased cerebral blood fluid in prefrontal cortex) Hypofrontality: ADHD (not mood disorder) Bipolar disorder Major depressive disorder Schizophrenia - negative symptoms In schizophrenia: Smaller thalamus -- sensory input goes through thalamus as relay station to rest of cerebral cortex, so there's going to be a dulled affect Larger ventricles - correlated with lower gray matter volume Dorsolateral prefrontal cortex matures more slowly; this region is involved in aspects of planning and decision-making Premature gray matter loss; already start out with larger vertices typically; what really matters is behavior and thought patterns though, not necessarily ventricle size

Rates of psychiatric symptoms are higher for females than for males, primarily because females are more likely to be depressed

High rates are also evident in 18-25 year olds because certain psychiatric disorders (ex: schizophrenia) appear in adolescence and young adulthood

Emotional Memories

High-arousal events (scary or exciting) create stronger memories Epinephrine (adrenaline) drives this effect; propranolol, an antagonist, prevents this memory boost Emotional memories can have tunnel vision (e.g. weapons focus effect, where criminal focuses on the scariest part of that experience, but not some of the peripheral details) Connectivity between amygdala and hippocampus is important for strengthening emotional memories We may be able to prevent PTSD by inhibiting epinephrine and/or interfering with consolidation of traumatic memory

Hippocampal neurons

Hippocampal neurons are also responsive --there may be even more specificity when you put up an Aniston face, that person's neuron is going to respond more if it's in the hippocampus - medial temporal lobe The inferior temporal lobe is near the FFA, but also close to the medial temporal lobe, where the hippocampus is Parallel processing of ventral (where/how) and dorsal (what streams); Anatomical hierarchy of visual areas in human and non-human primate: 40-50% brain real estate is devoted to vision; we have 32 visual cortical areas, 2 visual subcortical areas, and 187 anatomical connections (most reciprocal)

RESULT OF ALLIE'S STUDY

Hippocampal patterns were LESS stable after interrupted videos than full videos; levels of activation of hippocampus after both full and interrupted videos were comparable

How are sensory RFs identified?

How do they compare to visual RFs? Recall from neuroanatomy week: gray matter has interneurons and motor neurons that send axons to muscles, while white matter has myelinated axons going up and down the spine Touch receptors go to dorsal roots, go up spinal cord, to medulla, to midbrain, and then to the primary somatosensory cortex (Which is in the parietal lobe) Pain is the discomfort associated with tissue damage Just be familiar with these regions:

"How Sleep Affects Your Emotions" Video

How does lack of sleep impact emotional brain? Several years ago, conducted rain imaging study, in which they either sleep deprived or healthy adults, and next day you place them inside MRI saannner, and looked at how the emotional brain was reacting; They looked in particular at t he amygdala, which is one of the centerpiece regions for the generation of strong emotional reactions, including negative emotional reactions When they looked at people with full night's sleep, they saw appropriate, moderate degree of reactivity from the amygdala; but in those who were sleep deprived, that deep emotional brain center was hyperactive; amygdala wa s almost 60% more responsive under this case; This lead to discovery that there's another region of the brain involved in this; the prefrontal cortex, which is like the CEO of your brain, and it's very good at making high level executive top down control decisions and reactions, and is one of most evolved regions of brain, and it also controls the amygdala, the deep emotional center In those who had full night of sleep, there was nice connection btw the prefrontal cortex and amygdala, but in those ppl who were sleep deprived, that connection has essentially been severed, and as a consequence, the amygdala was responding far more reactively due to lack of sleep Almost as though, without sleep, we become all emotional accelerator, and that seems to be the reason why we become emotionally unravelled when we Turns out that there's something good that happens when you get your sleep back; sleep, particular REM sleep, offers form of emotional first aid, because it's during sleep that we take emotional experiences that we have during the day, and that acts like a nocturnal soothing body, taking ithe sharp edges off of those experience; Perhaps it's time during sleep that provides that form of emotional convalescence

Scientists are Still Searching For Animal Models of Depression

Human depression is influenced by many genes Learned Helplessness: one type of animal stress model where animal is exposed to repetitive stressful stimulus (ex: electrical shock) that it can't escape; learned helplessness is linked to decrease in serotonin function and mechanisms that control release of dopamine Removing olfactory bulb from rodents creates model of depression; resulting in irritability, references for alcohol, and elevated levels of corticosteroids

Study that lends some evidence for the Schachter-Singer Theory

Hypothesis for this experiment: Do circumstances provoke autonomic arousal? Do we attribute arousal to a particular emotion based on who and what is around us? Yes, the hypothesis states. Methods: Double-blind randomized control study Injected with epinephrine (which produces arousal) or saline They were told that "it might affect your heart rate" or told nothing Then the subjects then report on their emotion; They did this while near angry or happy confederates/actors Outcome: The subjects that were warned about the injection effects reported feeling no emotion Subjects not warned about the injections effect had an emotional reaction The emotion of the subject matched that of the confederate Implications: Reflect on surroundings, awareness, biases going into a situation Dr. Lebar uses fMRI to measure brain responses

Schachter-Singer Experiment:

Hypothesis: circumstances provoke autonomic arousal; we then attribute arousal to a particular emotion on the basis of context Test: Activate sympathetic nervous system with an injection of epinephrine to see whether the participants, some informed about the drug's effects (control), and some uninformed about the drug's effects, experience one particular emotion as they fill out forms; to test the hypothesis that emotional experience is determined by cognitive processes, expose the participants to a confederate who acts either angry or happy while filling out the forms Result: participants who were warned about the injection's effects reported no emotional reaction, while those not warned reported more intense emotional reactions; however, among participants who weren't warned about effects of injection, which emotion they experience tended to match that of the confederate Conclusion: while autonomic responses can intensify emotional experience, they can't explain why we have different emotional experiences in different situations; rather, our cognitive analysis of environment affects which emotion we experience Such findings contradict James-Lange theory that feelings of anger/elation are associated with unique set of autonomic reactions Shcachter and Singer concluded that participants experienced epinephrine-induced physiological arousal as whichever emotion based on their cognitive assessment of the situation *Thus, emotional states are results of interaction between two factors: physical arousal and cognitive interpretation of concurrent context Another outcome was that participants receiving epinephrine reported more intense emotions than other participants who were given saline

Hypothesis: the sound waves of different frequencies cause ripples at different places on the basilar membrane Experiment: Open a human cochlea and add a reflective fluid Bounce intense flash of light off of basilar membrane during vibration at ovular window Record the displacement of reflective fluid to measure movement of basilar membrane Result: "standing waves" are observed on basilar membrane, their position corresponding to frequency of the vibration Conclusion: Frequency of a sound is encoded by specific location on the basilar membrane that shows the largest displacement in response to the sound; high frequencies displace basilar membrane tat base of cochlea; low frequencies displace at the apex (called place coding)

Learning Objectives

Identify the major structures and functions of visual pathway -- from the eye to the what and where streams Describe techniques to strengthen eyesight and reduce visual impairment, including light exposure, focus and smooth pursuit Contrast the two types of photoreceptors, their distribution across the retina and perceptual consequences, such as the blind sport, visual acuity Describe the kinds of light stimuli that best excite or inhibit neurons in the retina, LGA, striate and extrastriate cortex Explain how lateral inhibition in the retina can sharpen vision while also making us susceptible to optical illusions Discuss the contributions made by patients like H.M. (memory) and D.F (vision) *Distinguish eyesight from visual perception and describe the relationships between vision, mood and sleep; what we see affects our emotions

Propranolol As an Emotional Memory Suppressant

If people are treated with propranolol (a beta-blocker that blocks the effect of epinephrine), the capacity for emotional enhancement of memory disappears (while treated people don't perceive the memory as being any less emotional, rather, the drug interferes with ability of stress hormones to enhance memory/blocks memory-enhancing effects

How Experience Regulates Gene Expression in Developing and Mature Brain

In pigs, genetically identical clones and genetically identical mice raised in different laboratories behave very differently on variety of tests While all cells in body have complete copy of genotype, each cell only uses a small portion of those genes at any one time (when cell uses particular gene to make protein, the cell has expressed that gene) Epigenetics: study of factors that affect gene expression without making any changes in the nucleotide sequence of the genes; same protein is produced, but amount of protein can vary, leading to variation in brain development) Experiment in Which Maternal Care Affected Mouse Behaviors: Hypothesis: behavior of genetically identical male mice can be affected by prenatal environment and/or mothering they receive after birth Experiment: take genetically identical mouse embryos of Black6 strain, implant them into womb of foster mother of either their own strain or another; after birth, transfer half of males to be raised by either Black6 female or Balb female, and when males grow up, measure their behavior on test in which Black6 and Balb mice normally differ Result: males of black6 strain carried and raised by mothers from albino strain show significant differences in several behaviors, including maze running, measures of anxiety Conclusion: since various males are genetically identical, their different behaviors are due to the effect of different prenatal environmentals and postnatal experiences: DNA Methylation: chemical modification of DNA that doesn't affect nucleotide sequence of gene, but makes that gene less likely to be expressed (ex: poor maternal care produces heightened stress hormone response in rodent pups by inducing methylation of glucocorticoid receptor gene in brain; this response may be similar in humans subjected to early childhood abuse):

Vomeronasal System in Rodents Specifically

In rodents, sensory neurons of VNO make hundreds of different vomeronasal receptor proteins, forming two families of GPCRs called V1R and V2R; these receptors are very sensitive (able to detect low levels of pheromone signals) From VNO, info is transmitted to accessory olfactory bulb, which projects to medial amygdala and hypothalamus (these structures are crucial in governing emotional and sexual behaviors, and in regulating hormone secretion)

Extrastriate Cortex

Many surrounding regions of the cortex that surround the primary visual cortex are largely visual in function; these visual cortical areas are called the extrastriate cortex Regions of extrastriate cortex process different aspects of visual perception (ex: color, form, location, movement)

"The Nature of Seeing" Video

In terms of vision, the brain sees only patterns of light, so there's a difference between what your eyes receive and what your brain sees Context affects how we see images The visual system must rely on context at all levels, because vision is a problem that mathematicians have deemed "ill-posed," which means that a variety of possible causes may be responsible for the same visual scene merely because of geometry and light Brain must use typical features in the world to develop approximations in order to interpret visual scenes In order to recognize an object, your brain has to be able to be able to separate the features that define it from those that don't (ex: a shape, like a square is composed of four edges, and we still recognize the square even if it's rotated or shrunk; thus, the square is invariant to these transformations) The first neurons in the visual pathway respond best to bright spots on dark backgrounds, or dark spots on bright backgrounds in certain locations of the visual field Many neurons in the primary visual cortex respond to edges; one hypothesis is that they do this by receiving input form a set of neurons, each of which responds to, for example, bright spots on a dark background, arranged in a line; if all these neurons respond, they send a signal to another neuron that will respond when all of its input neurons are firing (these types of cells are called simple cells) There are also neurons in the primary visual cortex that respond to lines and edges in a way that's invariant with their respective translations, at least within a small window (these types of cells are called complex cells; one hypothesis as to how these cells arise is that they receive input from set of simple cells) One theory as to how the brain brain develops responsiveness to complicated features in the natural world is by building hierarchies of these operations, alternating assets of simple and complex cells that construct features and develop invariance to them Given this, we would expect to see regions of the cortex that respond to larger and more complicated stimuli and are invariant with respect to more complicated changes; We have neurons in our brain that respond to images of specific people, independent of what they're wearing or their surrounding environment; this computational structure has been used to develop computer algorithms; One of the most important questions for visual neuroscience is how the brain processes context; context can have important effects Your brain can't resolve the questions of in what context objects appear, and what features appear together, based purely on what your eyes receive;

Neurogenesis: olfactory neurons regenerate every 4-6 weeks

In the adult brain, neurogenesis happens in the olfactory system How do we improve our sense of smell? Exercise, increasing blood flow and social interactions increase the regeneration rate of these olfactory neurons Studies show that breathing just through your nose has health benefits, and breathing through your mouth poses health detriments Subventricular zone: when dopamine levels are high enough, stem cells spit out neuroblasts that settle into olfactory mucosal lining (cribriform plate, Fig 6) Studies show being in a new relationship, greater dopamine, testosterone and estrogen and heightened sense of smell:

Example of Lateral Inhibition's Role in Gray Band Optical Illusion

In the figure below, ganglion cells stimulated by right-hand edge of each dark band are inhibited by the neighboring photoreceptors stimulated by the lighter band next door; thus ganglion cells stimulated by right edge of bar report receiving less light than they actually do (right edge looks darker), and conversely, left edge of each bar appear darker than rest of bar: **The phenomenon of lateral inhibition demonstrates that our visual experience is not merely a simple reporting of the physical properties of light; our perception of light vs. dark is created by brain in response to numerous factors (ex: surrounding stimuli)

"Smell: an Overview" Video:

In the late 1980s, polymerase chain reaction (PCR) revolutionized molecular biology by providing a way to replicate small amounts of genetic material in order to study them. Richard Axel and Linda Buck employed PCR to hunt for odorant receptors. Axel and Buck scanned the genetic material contained in rats' olfactory neurons looking for sequences similar to those encoding the receptor family. In 1991, they isolated 18 unique receptor genes that were members of this family but were found only in olfactory sensory neurons. Those 18 were the first of what turned out to be more than 1000 genes in rodents encoding smell sensors, more commonly referred to today as olfactory receptors. discern the difference between remarkably similar odor molecules. By 2002, they had established that the receptors represented a "super family" of more than 1000 individual proteins. By 1999, the scientific community knew that each receptor could in fact detect multiple molecules differing from one another only slightly. That ability greatly increased the number of detectable odors The discovery that individual receptors can respond to many different molecules was the key to understanding how a limited number of receptors allows us to detect and discern a vast number of odors. What's more, any given odor molecule activates multiple olfactory receptors. Perceiving smell begins with olfactory receptors in the nose and ends in the brain. Each smell activates a specific combination of olfactory neurons, which the brain decodes as a particular aroma. This "combinatorial" coding allows us to detect many more smells than we have specific receptors. Each chemical odorant triggers its own unique pattern of neural activity, leading to our perception of a particular smell. What's more, smell signals radiate to deeper regions of the brain, including the amygdala and hippocampus, areas critical for emotion and memory — one reason smells can evoke such powerful feelings. Patients with some neurodegenerative disorders including Alzheimer's disease and Parkinson's disease frequently struggle to detect and identify smells. Although the vast majority of olfactory receptors exist only in the nose, scientists have found some receptors in other tissues including the lungs, kidneys, skin, heart, muscle, colon, and brain. As a result, scientists are beginning to posit that they serve not just as smell receptors but as more general chemical sensors. The discovery of olfactory receptors opened a window on our sense of smell potentially leading to a better understanding of chemical signaling throughout the body.

Blind British Soldier 'Sees' with his tongue

Lance Corporal Craig Lundberg, 24 lost his sight after being struck by a rocket-propelled grenade while serving in asra in 2007 Glasses have a video camera that transmit electrical pulses to a lollipop on his tongue that cause a tingling sensation. "It feels like licking a 9-volt battery like popping candy". He interprets the different strength of the tingles into visualizations of his surroundings and objects "You get lines and shapes of things. It sees in black and white so you get a 2D image on your tongue -- it's a bit like a pins and needles sensation." H can read words, make out shapes and walk without sight

Hermann-Grid Illusion

Lateral inhibition affects light perception and some use it to explain the Hermann Grid Illusion

Studies Discovering Long-Term Potentiation:

In this experiment, electrodes were placed within the hippocampus, situated so that researchers could stimulate a group of presynaptic axons and record electrical response of group of postsynaptic neurons; Normal low-level activation of presynaptic cells produced stable and predictable excitatory postsynaptic potentials (EPSPs); However, when a brief high-frequency burst of electrical stimuli (called a tetanus) was applied to presynaptic neurons, producing a high rate of action potentials that drove the postsynaptic cells to fire repeatedly, the postsynaptic cells produced much larger EPSPs, and synapses appeared to have become stronger and more effective; Tetanus: An intense volley of action potentials that can change synaptic strength for a long time This stable, long-lasting enhancement of synaptic transmission is called long-term potentiation:

Have a broad understanding of the historical perspectives on the relationship between the mind, behavior and biology.

In-Class Notes/Lectures: Herotodus left documents of mummifications, and they could observe the heart; around the same time, Hypocrates, (460 BCE) was referred to as the "father of medicine" Plato said the brain was a 'vital principle' and that the spinal cord controlled a vital force Aristotle said that the brain was there to "cool the heart"; and this cooling apparatus might bI'm e linked to actual intelligence; thought the heart was the 'seat of mental capacities' Plato, Aristotle, Galen, Descartes, Gall, Flourens, Broca, Wernicke Data and analytical approach showed that there was an impact because of what he did to the heart Textbook Material: Plato: vital principle Aristotle: The brain cools the heart (a chicken could live without its head but not without its heart) Hippocrates: four "humors" = black bile, yellow bile, phlegm, and blood. When these humors were in balance, a person was healthy; when they were unbalanced, disease took over. Hippocrates identified the brain as the analyst of the outside world, interpreter of consciousness, and the center of intelligence and willpower. Galen: 130 C.E. physiology experiences, dissected animals/anatomy, how spinal cord connects to body, coined "lesions" Descartes: animals behave like machines (reaction/autonomic response), free will, dualism (body and mind) Gall: (analogy) skilled anatomist, traits determined by brain size (credit between anatomy and function) Flourens: 1794, used electricity from Gall's findings (experimentation) Broca: left frontal area language speech Wernicke: understanding language Thinking and emotions can be traced back to the Ancient Greeks due to archeological findings History of medicine is hugely biased towards western documentation Attitudes towards humans and animal experimentation has changed over time William James: associated with a true start to the scientific field that relates behavior to boldly processes

Discuss the general changes in sleep from infancy across development to elderly ages.

Infants: takes 16 weeks to get to 24 hour rhythm, shorter sleep cycles, largely spent in REM (50% of sl eep in REM), can move directly from being awake into REM sleep Puberty: circadian rhythm shifts to sleep later in the day; 7 to 8 hours Elderly: total amount of sleep declines and awakenings increases Stage 3 sleep: half as much as young adult Disappears by 90

How the Stress Response Progresses in Stages

Initial response to stress is the 'alarm reaction,' in which the hypothalamus activates the sympathetic nervous system to ready the body for action (fight-or-flight system) (1) Sympathetic system stimulates core of adrenal gland (called adrenal medulla) to release the hormones epinephrine (adrenaline) and norepinephrine (noradrenaline); these hormones act on many parts of body to boost heart rate and other physiological processes that prepare body for action (2) As another part of alarm reaction, hypothalamus stimulates anterior pituitary to release hormone that drives outer layer of adrenal gland (adrenal cortex) (3) Activation of this hypothalamic-pituitary-adrenal axis (HPA axis) results in release of adrenal corticosteroid hormones (such as cortisol) These hormones act more slowly than epinephrine, but als prepare body for action, releasing body stores of energy Glucocorticoid receptors (those that respond to cortisol) are found in many locations in brain, where they mediate formation of memories associated with stress and fear:

Hippocampus and STM/LTM:

Intact hippocampus is required to consolidate declarative STMs into LTMs (info is transformed into a different format)

Molecular Mechanisms Involved in Detection of Sour Tastes

It is believed that the protons (H+, hydrogen ions) that acids release interact with special acid-sensing ion channels (ex: ionotropic receptors) to alter polarity of taste cells and alter transmitter release All sour-sensitive taste cells have a certain type of ion channel protein, in which an inward flow of protons depolarizes cell

The Amygdala and Emotional Learning

It's easy to reliably elicit fear by using classical conditioning, in which subject is presented with stimulus such as light or sound that's paired with a brief aversive stimulus (such as mild electric shock) Fear Conditioning: such studies of fear conditioning allowed researchers to develop map of the neural circuitry of emotional learning, which revealed that amygdala is key structure in this Amygdala: A group of nuclei in the medial anterior part of the temporal lobe; each of these about a dozen nuclei has a distinctive set of connections Lesioning just central nucleus of amygdala in rats prevents blood pressure increases and freezing behavior in response to conditioned fear stimulus Amygdala is also crucial for appetitive learning (conditioned positive emotional reactions to attractive stimuli) Overall, amygdala helps form associations between emotional responses and specific memories of stimuli that are stored elsewhere in the brain "Low Road" and "High Roads" of Emotional Processing: "Low Road": A direction projection from the thalamus to amygdala, nicknamed the 'low road' for emotional responses in the original fear-conditioning studies; this bypasses conscious processing and allows for immediate emotional reactions to stimuli "High Road": Alternative "high road" pathway routes incoming info through sensory cortex, allowing for processing that, while slower, is conscious, fine-grained, and integrated with higher-level cognitive processes Role of Amygdala in Fear: When people are shown visual stimuli associated with pain for fear, fear-specific activity is observed in amygdala neurons, and activation of amygdala may be observed even if person is not consciously aware of the stimuli Additionally, when people view facial expressions of fear, electrophysiological responses occur more quickly in the amygdala than in visual cortex People who have temporal lobe seizures that include the amygdala report that intense fear accompanies seizures Electrical stimulation of temporal lobe sites during brain surgery may elicit feelings of fear Neural mechanisms of fear conditioning also play role in PTSD Capgras Delusion: rare condition in which people believe that their significant others have been replaced by imposters; some cases result from brain damage that robs afflicted person of privileged low-road connection between visual stimuli and emotions they would normally elicit Patient S.M. and Loss of Fear: The fearlessness that she displays seems due to loss of amygdala; hre condition causes accumulation of calcium deposits in amygdala, eventually destroying nuclei in both cerebral hemispheres Also very poor at recognizing facial expressions of fear in others, but recognizes other emotional expressions:

Nose plugged up?

It's like you can't taste anything. And it might not even look good to drink or eat. Reduced smell and taste sensations leads to paying attention to nutrition and weight

Korsakoff's Syndrome and Damage to Medial Diencephalon

Korsakoff's is a memory disorder caused by thiamine deficiency generally associated with alcoholism; thiamine supplements can prevent further deterioration of memory, but cannot cure it;

Neurons at different levels of the visual system have very different receptive Fields (RFs)

LGN (lateral geniculate nucleus) neurons send axons to the primary visual cortex, v1, whose cells require more-specific, elongated stimuli; they like long stimuli V1 is in the back of the brain, part of the occipital lobe; v1 is stimulated by bars and movement V1 Simple Cortical cells -- also called bar or edge detectors -- respond to an edge or bar of a particular width, orientation, and location; they like bars, and they help you to detect edges; simple bars: V1 Complex cortical cells -- also respond to a bar of a particular width and orientation, but may be located anywhere in the visual field; these like bars, thinner, vertical, thick, moving

Long-Term Potentiation Video:

LTP is process by which synaptic connections between neurons become stronger with frequent activation LTP is a way in which the brain changes in response to experience, and thus may be a mechanism underlying learning and memory Glutamate-Dependent LTPs: Involves glutamate receptor (NMDA receptor); in NMDA-receptor dependent LTP, glutamate release first activates a subtype of glutamate receptor (AMPA receptor) NMDA receptors are located nearby these AMPA receptors, but are not activated by low levels of glutamate release, because the ion channel of NMDA receptor is blocked by Mg2+ ion If frequent action potentials cause greater stimulation of AMPA receptors, however, this will cause the postsynaptic neuron to depolarize, which eventually causes the voltage-dependent magnesium blockage of NMDA receptor to be removed, allowing Ca2+ ions to flow through the NMDA receptor This influx of Ca2+ initiates cellular mechanisms that cause more AMPA receptors to be inserted into the neuron's membrane The new AMPA receptors are also more responsive to glutamate and allow more positively charged ions to enter the cell when activated Now, the postsynaptic cell is more sensitive to glutamate because it has more receptors to respond to it Additionally, there are signals that travel back across the synapse to stimulate greater levels of glutamate release; All of this makes the synapse stronger and more likely to be activated in the future This process is also associated with changes in gene transcription in the neuron, which can lead to production of new receptors or modifications to structure of the cell These changes are important for making the increased responsiveness of LTP long-lasting

Visual experience isn't a simple reporting of the properties of light

Lateral inhibition: cells inhibit info from neighboring cells, producing an effect of contrast at the edges of those regions (ex: you can have an off center cell next to an on-center cell, so they can really maximize each other); *we don't talk much about amicron cells, but they're there (these cells are important to de-amplify some inputs) Bipolar cells inhibit one another Ganglion cells then report less info about what is actually being seen; they don't have exactly the same info as the photoreceptors; by the time it reaches them, it's not the same Our perception is created by the brain in response to many factors, even at this "low level" (ex: eye, retina); high level is going to the cortex, temporal lobe

Procedure:

Learning phase: View 70 full videos Reactivation Phase: View 35 full and 35 interrupted videos Testing Phase: verbal recall memory test about full videos

Polygraph Test

Lie-detector test in which multiple physiological measures, such as changes in respiratory rate, hearse rate, blood pressure, and skin conductance are recorded; test assumes that people have emotional responses when lying because they fear detection and/or feel guilty about lying

Lens

Light passing through the cornea is further refracted by the lens, which changes shape to fine-tune the image on the retina; this further helps focus the image on the retina Refraction: The bending of light rays; basis of eyeglasses, telescopes, microscopes, etc. Farsightedness: As mammals age, their lenses become less elastic and thus less able to bring nearby objects into focus; this problem can be corrected by holding objects further away or wearing glasses

Understand that a molecular clock in cells (clock/cycle and per/cry) generates the daily circadian rhythm.

Light to Feedback Loop Process: Light goes through the specialized (retinal) ganglion cells (found at the retina at the back of the eye; retinal tissue is nervous tissue), which leads directly to the scn (biological clock), and then every cell in every organ is affected, and then there's a feedback loop The clock and cycle proteins form a dimer, and they then are now instructed on where they can enter the nucleus, then in the nucleus, they transcribe some genes into the period and cryptochrome, which leave the nucleus and then form a dimer, and then per and cry breakdown and release clock and cycle and then the cycle goes again Process (takes about 24-hours to complete, which drives cycle of SCN cells): Neurons in the SCN make proteins Clock and Cycle, which bind together to form a dimer Clock/cycle dimer then bind to cell's DNA to promote transcription of other genes, including period (per) Proteins made from these genes go back to inhibit the action of Clock and Cycle Because those inhibitory proteins degrade with time, eventually the inhibition is lifted, and the cycle starts over again

How Cocaine Affects Synapses in the Brain:

Limbic System: contains the brain's reward circuit/pathway, which linked together a number of structures that link together structures that control and regulate our ability to feel pleasure; When the reward circuit is activated, each circuit relays electrical and chemical signals; While dopamine surges in response to natural rewards help the brain learn and adapt to the world, drugs are able to hijack this process; Cocaine's Effects on Synapses in the Limbic System: When using cocaine, the drug quickly enters the brain, where it blocks the transporters on the presynaptic cell; Since dopamine can't re-enter the presynaptic cell, it begins to accumulate in the synapse, where it can reach abnormally high levels and remain there much longer than usual; This causes the postsynaptic cell to become hyperactivated, which produces a feeling of euphoria, which creates a powerful association between cocaine and pleasure, making person want to repeat the experience of taking the drug

Dorsomedial Thalamus:

Limbic system structure that's connected to the hippocampus

Case of Patient D.F

Lost ability to perceive faces and objects as result of carbon monoxide poisoning, but was still able to reach and grasp objects under visual control Thus, DF's visual ventral "what" stream was devastated (damage to the region on the border of the occipital and temporal cortex) while her dorsal "where" stream was unimpaired; images of her brain revealed damage concentrated in ventrolateral occipital cortex of her brain, and she had shrunken gyri and enlarged sulci DF suffered damage to the ventral stream of the primary visual cortex, and, as a result, she wasn't able to recognize objects, but she could grasp them This condition is similar to the cortical damage that causes blindsight Her dorsal stream told her where objects were and guided her movements to use these objects correctly:

Lower back pain

Low back pain causes more global disability than any other condition Acute back pain of often defined as lasting less than 4 weeks Subacute back pain lasts 4 to 12 weeks Chronic back pain lasts more than 12 weeks Despite an overall lack of evidence to support its efficacy, opioids continue to be prescribed to treat acute LBP when patients seek medication evaluation (almost 14% of insured patients were prescribed this for LBP) An estimated 1.4 million people in US had a substance use disorder related to prescription opioids in 2019; only 22% receive "tailored treatment"

The frequency of hearing loss is designated as

Low(<500 Hz) Middle (501-2000 Hz) High (>2000 Hz)

Treatment of Macular Degeneration

Macular degeneration is visual impairment caused by damage to retina; The most common type is "dry" macular degeneration and is caused by atrophy of retinal pigmented epithelium that results in death of overlying photoreceptors "Wet" macular degeneration is more severe, in which abnormal growth of retinal capillaries leads to detachment of retina and/or death of photoreceptors (this damage is restricted to fovea, but because visual acuity is poor for rest of retina, vision is significantly impaired) Supplemental vitamins and antioxidants can slow the disease slightly

Vomeronasal System in Terrestrial Vertebrates

Majority of terrestrial vertebrates (mammals, amphibians, and reptiles) have secondary chemical detection systems that are specialized for detecting pheromones (this is called the vomeronasal system): Pheromones: Chemical signals that are released outside the body of an animal and affect other members of the same species Receptors of the vomeronasal system are found in the vomeronasal organ (VNO) near the olfactory epithelium Vomeronasal Organ (VNO): Collection of specialized receptor cells, near to but separate from olfactory epithelium, that detect pheromones and send electrical signals to the accessory olfactory bulb in the brain

Range of Frequencies Detected by Mammals

Mammalian species have a wide range of frequencies from infrasound (less than 20 Hz) in elephants and whales to ultrasound (greater than 20,000 HZ) in bats, etc.; these sounds serve evolutionarily advantageous purposes

Patient K.C

Man who suffered brain damage in motorcycle accident, and couldn't retrieve any personal memory of his past, but his general knowledge remained unimpaired (ex: conversed well and played chess well but didn't remember where he learned chess) Experienced damage to left frontoparietal and right parieto-occipital cerebral cortex, shrinkage of left and right hippocampus and nearby cortex; his anterograde declarative amnesia was most likely attributable to this bilateral hippocampal damage; however, this didn't explain his selective loss of autobiographical, episodic memory (this was attributable to injuries to front and parietal cortex) K.C.'s case showed that some declarative memories are stored in the cortex and that there are two different subtypes of declarative memory:

How Different Emotions Activate Different Regions of the Human Brain

Many forebrain areas are consistently implicated in varying emotions love increased activity in the insula and anterior cingulate cortex and reduces activity in posterior cingulate and prefrontal cortices; Given its role in fear, amygdala showed reduced activity when people were contemplating their romantic partners Activity of anterior insular cortex has been implicated in conscious experience of these nuanced emotional states; impairments in emotional awareness (alexithymia) are associated with dysfunction of the insula Another study found brain activation during four kinds of emotion in the insula, cingulate cortex, and prefrontal cortex; such studies suggest that there is no one-to-one relation between specific emotion and activity of a specific brain region; Each emotion involves differential patterns of activation across a network of brain regions associated with emotion; there is overlap among patterns

Summary of Learning and Memory

Many regions of the brain are involved in learning and memory; Different forms of memory rely on different brain mechanisms The same brain structure can be apart of the circuitry for various forms of learning

Meissner's Corpuscles

Meissner's corpuscles and Merkel's discs mediate most of our ability to perceive the forms of objects we touch; these are skin receptor cell types that detect light touch, responding especially to changes in stimuli

Allie's Research: How Prediction and Surprise can Change Memories:

Memories can be changed over time; On one hand, this can result in distortion and false memories On other hand, we need knowledge to be malleable, so this can be a good thing; this is the Surprise can be a trigger for memory change; it's a signal that something has changed about the world that contradicts our prior experience How do we learn from errors? Sometimes we need more detailed feedback Try to solve puzzles Try to take a familiar route home and take detour As scientists, we constantly generate hypotheses about how the world works, and then test them Reconsolidation Theory: We begin with consolidated memory, and if we reactivate that memory, creating a window of opportunity for the memory to modify, this results in a destabilized memory This destabilized memory can be reconsolidated However, if we screw with the memory while it's in its destabilized state, this can result in an altered memory Surprising reminders create the opportunity for change

Short-Term Memories (STMs)

Memories longer than sensory buffers; This form of memory usually lasts only as long as rehearsal continues (in the absence of rehearsal, they only last 30 seconds), and working memory is considered a portion of STM where info can be manipulated Once the STM is gone, it's gone for good Working memory: Subset of STM; refers to the ability to actively manipulate information in your short-term memory, maybe by retrieving info from your LTM to make use of the info, solve a problem, etc.); info can be analyzed by some 'executive' part of your mind Flow of working memory is supervised by a part of the mind called an executive function

Characteristics of PTSD

Memories of horrible events intrude into consciousness, producing same intense visceral arousal that the original event caused

Extraocular Muscles

Three pairs of muscles that extend from outside of eyeball to bony socket of the eye that control the movement of the eyes; fixing gaze on still or moving objects requires meticulous control of these muscles to pin down the visual image on the retina

How the Middle Ear Concentrates Sound Energies

Middle Ear: The cavity between the tympanic membrane and the cochlea; collection of small structures comprised of membrane, muscle, and bone that links the ear canal to the neural receptor cells of the inner ear Consists of taut tympanic membrane (eardrum) sealing end of ear canal and chain of tiny bones called ossicles that couple tympanic membrane to inner ear at specialized patch of membrane called oval window Tympanic Membrane: Also called eardrum; taut membrane at inner end-of ear canal that captures sound vibrations in air Ossicles: Three small bones (incus, malleus, and stapes) that transmit vibration across the middle ear, from the tympanic membrane to the oval window; tensor tympani and the stapedius attach to the ends of the chain of ossicles Oval Window: The location on the cochlea at which vibrations are transmitted from the ossicles to the interior of the cochlea (1) Sound waves in air strike tympanic membrane, causing it to vibrate with same frequency as sound; (2) Then, ossicles start moving too, and they concentrate and amplify the vibrations, focusing pressures from large tympanic membrane onto small oval window (this is crucial for converting vibrations in air into movements of fluid in inner ear) Volume Control of Middle Ear: Middle ear is equipped with volume control, protecting against damagingly loud noises; Before sound arrives, brain signals the tensor tympani and stapedius (two small muscles attached to ends of chain of ossicles) muscles to contract, stiffening chain of ossicles and reducing effectiveness of such sounds These muscles activate before we produce self-made sounds, which explains why we don;t perceive our own sounds as distractingly loud

Severity of hearing loss in decibels (dB)

Mild: 26-40 dB Moderate: 41-55 dB Moderately severe: 56-70 dB Severe: 71-90 dB

Three Types of Evidence that Suggest LTP Underlies Some Forms of Learning and Memory

More complex declarative and procedural memory traces involve large networks of neurons, so LTP isn't the only mechanism of learning, but three types of evidence suggest that LTP plays a role in some forms of memory: Correlational Observations: These demonstrate that the time course of LTP is very similar to the time course of memory formation Somatic Intervention Experiments: Pharmacological treatments that impede LTP impair learning (ex: NMDA receptor blockade interferes with permanence in a certain test of spatial memory and other memory tests Mice that lack functional NMDA receptors in the CA1 region of the hippocampus have hippocampi that are incapable of LTP and hence their declarative memory is impaired Moreover, mice genetically engineered to overexpress NMDA receptors in hippocampus have enhanced LTP and enhanced long-term memory Behavioral Intervention Experiments: Most convincing evidence for link between LTP and learning is "behavioral LTP (shows that training an animal in a memory task induces LTP in the brain); However, usch research is often complicated because it's difficult to gauge where exactly to place the recording electrodes to detected LTP **Thus, this evidence suggests that LTP is a type of synaptic plasticity that is responsible for particular forms of learning and memory

Get Your Morning Sun Exposure:

More exposure to daylight may reduce nearsightedness in children; Outdoor recess plus 3 hours in natural light Dopamine prevents the eye from becoming elongated Sun exposure-- "enough" associated with reduction in some health conditions: type 1 diabetes, prostate cancer, hypertension, MS bipolar disorder, depression, and insomnia It helps to reset pineal gland -- biological clock

"What" and "Where" Streams of Visual Processing

Mortimer Mishkin and Leslie Ungerleider proposed that humans have two main visual processing streams, both originating in primary visual cortex: "What" Stream: Ventral processing stream responsible for visually identifying objects; includes regions of occipitotemporal, inferior temporal and inferior frontal areas (info about faces becomes more specific as stream process farther form; includes the fusiform gyrus "Where" Stream: Dorsal processing stream responsible for appreciating the spatial location of objects and visually guiding our movement towards them These two streams aren't completely separate; many cross connections between them

NMDA Receptor-Dependant LTP:

Most studied form of LTP occurs at synapses that use the excitatory neurotransmitter glutamate, which is dependent on a glutamate receptor subtype called the NMDA receptor

The Discrete Pain Pathway Projecting From the Body to Brain

Most tissues of body contain receptors specialized for detecting painful stimuli; these receptors are well-studied in the skin Nociceptors: when tissue is injured, the affected cells release chemicals that activate nearby pain receptors, called nociceptors, on free nerve endings specialized to detect damage Such chemicals also cause inflammation; many different substances in injured tissue (ex: serotonin, histamine, etc.) can stimulate these nociceptors Different nociceptors respond to various stimuli (ex: pain and/or changes in temperature)

Mice vs. Human

Mouse birth, or postnatal day (P)0 in a mouse = 3rd trimester in humans In a mouse, birth is not anywhere near birth in a human; the first ten days of life in a mouse kind of correspond to the third trimester in human fetal development

How to Avoid Impairment of Vision and Improve an Impaired Visual System

Myopia Reduction: evidence suggests that the reason some children develop myopia is due to certain environmental factors that cause the eyeball to grow excessively; new evidence suggests that indoor lighting may be the culprit of this With advent of indoor lighting, we have spent a lot of time looking at images that don't exactly match the composition of sunlight Children with myopia spend less time outdoors than other children do (increasing public school education in some nations correlates to increased rates of myopia) Thus, maximizing time outdoors (to a certain extent) can help improve/avoid myopia

NIH

NIDAH is a branch of the big NIH The National institute of Mental Health has commissioned these studies NIH Clinical Center, Center for Information Technology, and Center for Scientific Review have no funding authority

Selective Deficits in Prefrontal Cortex Function in Medication-Naive Patients With Schizophrenia

Naive = first time taking it During working memory (continuous performance task-CPTs): there are deficits in dorsolateral PFC activation but intact activation of posterior and inferior PFC, primary motor and somatosensory cortices (they were ok, those were intact) Shown frontal lobe regions from makak monkey vs human The most common psychopathologies: depression, bipolar disorder, and anxiety disorders Across what six characteristics are there disparities of psychopathologies: Sex Age Financial status Race and ethnicity Geography Education levels Percentage of US adults with major depressive episode in past year as of 2020, by age and gender; highest among those in range of ages 18-25 Percentage of adults in the US with depression from 2007 to 2016, by gender Percentage of adults in US with depression by ethnicity and gender Percentage of adults in US with depression by family income level and gender Percentage of US lesbian, gay or bisexual adults who reported a major depressive episode in the past year is very high Percentage of US veterans who had major depressive episode in opast year, are very high Percentage of adults in US with depression from 2013 to 201, by age

Conclusion of Study

Neurons at each level of the visual system combine input from neurons at lower levels to make progressively more complex receptive fields; thus, retinal and LGN neurons respond best to spots of light on the retina, while cortical cells respond best to lines of particular orientation, or lines that move in a particular direction

Tonotopic Organization

Neurons within all levels of auditory system, from cochlea to auditory cortex display tonotopic organization; they are internally arranged according to an orderly map of sound frequencies, from low frequencies (perceived as lower pitch, or "bass") to high frequency (perceived as higher pitched, or "treble") At higher levels of auditory system, auditory neurons aren't only excited by specific frequencies, they're inhibited by neighboring frequencies (results in sharper tuning of frequency responses of these cells), which helps us discriminate small differences in frequencies of sounds

Distinguish a neurotransmitter from a neuromodulator and when they are agonists or antagonists.

Neurotransmitters vs. Neuromodulators: Neurotransmitter: chemical messenger released from a neuron which diffuses across synaptic cleft to affect one or two postsynaptic neurons, a muscle cell, or another effector cell; it's reabsorbed by the presynaptic neuron (Ex: serotonin, acetylcholine, norepinephrine, dopamine, epinephrine) Neuromodulator: a chemical messenger released from a neuron in the CNS or PNS (adrenal glands) that affects groups of neurons or other cells; often acts through second messengers (more complicated) and can produce long-lasting effects; it can act as a neurotransmitter and often enhances the effects of neurotransmitters (ex: serotonin, dopamine, acetylcholine, norepinephrine, caffeine, cocaine) NT/neuromodulators can be both excitatory or inhibitory; it depends on the postsynaptic response, whether there's an action potential in the postsynaptic neuron (ex: norepinephrine and acetylcholine are both inhibitory and excitatory) Textbook Material: The nature of the postsynaptic receptors at a synapse determines the action of the transmitter (ex: acetylcholine can function as inhibitory or excitatory neurotransmitter at different synapses; at excitatory synapses, binding of ACh to one type of receptor opens channels for Na+ and K+ ions; at inhibitory synapses, ACh may bind to receptor that opens channels allowing Cl- to enter) Agonists: Molecules like neurotransmitters at a receptor are agonists; Antagonists: molecules that interfere with or prevent action of a transmitter are antagonists Note: each neurotransmitter binds to several different receptor molecules; (ex: ACh acts on at least four subtypes of cholinergic receptors)

How Sensory Brain Regions Influence One Another and Change Over Time

Often, use of one sensory system influences perception from another sensory system (ex: we can detect visual signal more accurately if it's accompanied by sound) Association Areas: many sensory areas in the brain, called association areas, process a mixture of inputs from different sensory systems (ex: so visual cells respond to auditory stimuli); Polymodal Neurons: Neurons upon which info from more than one sensory system converges; the convergence of info from different sensory systems on these polymodal neurons allows different sensory systems to interact Synesthesia: In some cases, stimulus in one sensory modality may evoke additional perception in another sensory modality (ex: musical note has both a sound and a flavor, or seeing a number evokes a color) Plasticity of Cortical Maps: Cortical maps change considerably as a result of experience (ex: professional musicians who played stringed instruments have expanded cortical representations of their left fingers) Some changes in cortical maps occur after weeks or months of use or disuse, arising from growth of new synapses and dendrites or from loss of others

How Receptor Neurons in the Nose Create Sense of Smell

Olfactory Epithelium: sheet of cells called olfactory epithelium lines part of nasal cavities; three types of cells are found in olfactory epithelium: supporting cells, basal cells, and olfactory receptor neurons Olfactory Receptor Cells: each olfactory receptor cell is a complete neuron, with a long dendrite that divides into branches that extend into the mucosal surface Odors dissolve into mucosal layer and interact with receptors Olfactory receptor proteins are variety of G protein-coupled receptors (GPCRs) that use second-messenger systems to respond to presence of odors

How Auditory Signals Run From Cochlea to Cortex

On each side of head, 50,000 auditory axons from cochlea comprise the auditory part of vestibulocochlear nerve (cranial nerve VIII); most of these afferent fibers carry info from IHCs (which each stimulate several nerve fibers) to brain Cell's Tuning Curve: Each of the IHC afferents has maximum sensitivity to sound of particular frequency, but can also respond to neighboring frequencies as sound is loud; brain analyzes activity from thousands of these units to calculate intensity and frequency of each sound

Two Types of Receptive Fields In Bipolar and Ganglion Cells

On-center/Off-surround: Refers types of bipolar and ganglion cells that have concentric receptive fields in which stimulation of center excites the cell, while stimulation of the surround inhibits it (illumination of both has little effect); when center is stimulated by light, bipolar cells respond with local graded potentials, and ganglion cells respond with action potentials Off center-On surround: Refers to types of bipolar and ganglion cells that have concentric receptive fields in which stimulation of the center of the cell inhibits it, while stimulation of the surround excites it (illumination of both has little effect); when the surround in these cells is stimulated, bipolar cells respond with graded local potentials, and ganglion cells respond with action potentials The antagonistic effects of center and surround are the reason why uniform illumination of the entire receptive field does not really affect ganglion cell activity (compared with well-placed small spot of light within cell's receptive field) Neurons in LGN (stimulated by RGC), also have these on-center/off-surround and off-center/on-surround receptive fields:

Stage Four: Synaptogenesis:

Once these cells take on the characteristics of neurons in cell differentiation, they begin making synaptic connections with one another; Synaptogenesis is the establishment of synaptic connections as axons and dendrites grow

Mammillary Bodies

One pair of limbic system structures that are connected to the hippocampus; serve as processing system that connects the medial temporal lobes to the thalamus, and from there, to other cortical sites

Ectoderm:

Outer cellular layer of developing embryo that gives rise to skin and nervous system;

How Hair Cells are Organized For Neural Signal Connections

Organized into single row of inner hair cells (IHCs) that are closer to central axis of coiled cochlea and outer hair cells; Fibers of vestibulocochlear nerve (cranial nerve VIII) contact bases of hair cells

Key message from last week about sensation and perception

Our brains are limited by what our sensory organs, e.g., touch receptors, can translate into electrical-chemical signals for our brains to make sense of, giving rise to our perception of the world --heat, pain, touch, etc. -- around us Chemical - smell and taste Electrical sensory systems: dogs have up to 300 olfactory neurons; dog:human = 300:700 olfactory neurons; dolphin: human up to 300:60 million olfactory neurons Dolphin: human up to 150K: 20 K Hz Pit vipers: humans 50 nm-1 mm; 300-700 nm Glabrous skin is specific for discriminative touch for proper grip control and determination of texture and shape

Why study memory?

Our memories are records of our lives, inscribed into our brains Our experiences make us who we are, our sense of self From an adaptive perspective, memory lets us learn from our experiences so we can predict the future and make better choices When our memory systems go wrong, it can cause amnesia, dementia, learning disabilities, false memories, phobias, PTSD, etc.

"Journey of Sound to the Brain" Video

Outer ear catches sound waves, which then travel through narrow passageway (the ear canal); Sound waves then reach the eardrum, which is membrane half the size of dime; they make the eardrum vibrate, which, in turn vibrates three tiny bones--the malleus incus, and stapes These bones amplify, increase sound vibrations and send them to the cochlea; this is filled with fluid, and the sound vibrations make this fluid ripple, which creates waves Hair-like structures called stereocilia sit on top of hair cell and are grouped together as hair cell bundles inside the cochlea; The hair cells inside the cochlea ride these waves, and the hair bundles are moved; the hair bundle on top of hair cell turns these movement into electrical signals As the hair bundles are moved, ions rush into the top of the hair cells, causing the release of chemicals at the bottom of the hair cells; The chemicals bind to the auditory nerve cells and create an electrical signal, which travels along the auditory nerve to the brain Different hair cells respond to different frequencies of sound; the hair cells at base of cochlea detect higher-frequency sounds, such as bass or flute, while hair cells toward top of spiral detect progressively lower-pitched sounds, such as trombone At the top/apex of the spiral, the hair cells detect the lowest pitched sounds, such as a tuba The auditory nerve then carries the electrical signal to the brain, which interprets the messages as sounds that we recognize and understand

The glutamate hypothesis also has some fixed support from observations in humans on glutamate receptor acting drugs

PCP produces phenomena strongly resembling both positive and negative symptoms Auditory hallucinations, strange depersonalization, disorientation, violence possible from delusions Similar limitations to this hypothesis and glutamatergic drugs don't reduce positive symptoms Mechanism of action: NMDA receptor antagonist - blocks Ca2+ channel, and therefore it blocks glutamate: Underactivation of frontal cortex and poor executive function tasks Again, schizophrenia likely involves circuits with different sensitivities, plasticity, structural and genetic variations, changes across development, and receptors

Ascending pathways for pain and temperature from the body to the brain

Pain info is carried by rapidly conducting myelinated A delta fibers and slow Nerve fibers send axons into dorsal horns: A-alpha nerve fibers = proprioception A-beta nerve fibers = touch A-delta nerve fibers = pain and temperature C-nerve fibers = pain, temperature, and itch They synapse on spinal neurons that project across the midline, then ascend to the thalamus Glutamate and substance P ("powder") are released in spinal cord to boost pain signals Pain is integrated in the cingulate cortex The periaqueductal grey may be the gatekeeper; it's where opioids act

Thalamus

Paired structures to either side of third ventricle, at top of brainstem, that direct the flow of sensory info to and from the cortex; **For most senses, info reaches the thalamus before being relayed to the cortex; info about each sensory modality is sent to a separate division of the thalamus The cortex directs the thalamus to emphasize some sensory info and suppress other info

Other Patient Examples:

Patient NA: physical lesion to these areas after an accident that involved a sword up the nose Korsakoff's syndrome: degeneration of these areas (and the frontal lobe), caused by alcoholism Those patients also confabulate, describing false memories, suggesting that they have trouble distinguishing between events that actually happened and were imagined

Characteristics of Tourrette's Syndrome

People with Tourette's Syndrome are hypersensitive to tactile, auditory, and visual stimuli Onset is early in life; mean age of diagnosis is 6-7 years, and syndrome is 3-4 times more common in males than in females People with Tourrette's often exhibit attention deficit hyperactivity disorder Children with Tourrette's display thinning of primary somatosensory and motor cortex representing facial, oral, and laryngeal structures, suggesting taht the tic mediated by these regions may be under inhibited by the cortex Genetics play crucial role in the disorder; among discordant monozygotic twin pairs, twin affected has greater density of dopamine D2 receptors in caudate nucleus of the basal ganglia; This suggests that differences in dopaminergic system, especially in basal ganglia may be important Treatments: treatment with haloperidol, a dopamine D2 receptor antagonist that's a first-generation antipsychotic drug significantly reduces tic frequency and is primary treatment for Tourette's DBS can also benefit people with Tourettes; battery-powered stimulating electrodes are aimed at targets in thalamus in regions associated with control of movement; activation of these electrodes brings dramatic and immediate relief

The Basics of Sound

Perception of repetitive pattern of local increases and decreases in air pressure as sound is caused by vibrating object (ex: person's larynx while speaking), and single compression and expansion of air is called one cycle

The Glutamate Hypothesis

Phencyclidine (PCP): drug found to be a potent psychotomimetic; produces phenomena strongly resembling both the positive and negative symptoms of schizophrenia (hallucinations, disordentation, etc.) PCP acts as an NMDA receptor antagonists, blocking the NMDA receptor's central calcium channel, thus preventing glutamate from having its usual effects; treating monkeys with PCP produces schizophrenia-like syndrome Other antagonists of NMDA receptors, such as ketamine, have similar effects; these observations allowed researchers to propose glutamate hypothesis of schizophrenia;

Pheromones and Humans

Pheromone-like phenomena: exposure to individual's bodily odors can shift women's menstrual cycles VNO is either vestigial or absent in humans If humans do communicate through pheromones, it's most likely using the main olfactory epithelium rather than the VNO TAARs: In mice, receptors in main olfactory epithelium called TAARs for trace amine-associate receptors respond to sex-specific pheromones instead of odors; TAARs have been also found in human olfactory epithelium; suggesting that perhaps we can detect pheromones through the olfactory epithelium Evidence suggests that odor is an important channel for human social communication

Anxiety Disorders: several types;

Phobic Disorders: intense, irrational fears that are centered on a specific object activity, or situation that person avoids Panic Disorder: characterized by recurrent transient attacks of intense fearfulness Some people who experience recurrent panic attacks have temporal lobe abnormalities, especially in left hemisphere; changes may be particularly clear in the amygdala Generalized Anxiety Disorder: persistent, excessive anxiety and worry are experienced for months

Photoreceptors Respond to Light By Releasing Less Neurotransmitter:

Photoreceptors in the dark continually release neurotransmitter onto bipolar cells; Thus, when light hits photopigment in the photoreceptor, it triggers chemical reactions that hyperpolarize the cell, thus causing the cell to release less neurotransmitter onto bipolar cells; **Light causes photoreceptors to release less neurotransmitter; visual system responds to changes in light (either an increase or decrease in intensity of light stimulates visual system, and thus hyperpolarization is as much a neural signal as depolarization is); Stimulation of rhodopsin by light hyperpolarizes the rods, just as stimulation of cone pigments hyperpolarizes them as well; *Note: the size of hyperpolarizing photoreceptor potential determines how much transmitter will be released to the bipolar cell This change in potential of photoreceptor cells is the initial electrical signal in the visual pathway

A free and readily available toll for modulating physiology to induce calmness is at our fingertips

Phrenic nerve: provides primary motor supply to the diaphragm, which is major respiratory muscle; it passes motor info to diagram and receives sensory info from it, so these tactile/stretch receptors in this muscle feed info to our brains through this phrenic nerve When you inhale, your diaphragm moves down, because of that, it creates more space in your cavity, and heart gets bigger, blood moves more slowly, and there are neurons in the heart (sinoatrial node neurons), which then tell the heart to beat faster Thus, if you inhaled a lot vigorously, it would increase heart rate When you exhale, your diaphragm moves up, cavity gets smaller so your heart has to constrict a bit, and as result, sinoatrial node neurons tell the heart to slow down How can you inhale and exhale to calm down quickly? By making your exhales longer or more vigorous than your inhales Inhale 3 counts, exhale 5 or 6 counts

Physical and Structural Changes at Synapses that Can Occur As A Result of Neuroplasticity:

Physiological changes: can be presynaptic, postsynaptic, or both; includes changes in amount of neurotransmitter released or in the number or sensitivity of postsynaptic receptors, resulting in either larger or smaller potentials Can take the form of inhibiting inaction of the transmitter by altering reuptake or enzymatic degradation Synaptic activity can be influenced by inputs from other neurons, causing extra depolarization or hyperpolarization of the axon terminals and thus, changes in the amount of neurotransmitter released Structural Changes: training can lead to the reorganization of synaptic connections (ex: can cause more active pathway to take over sites previously occupied by less active competitor) These changes may be observed through a microscope, as new synapses form or old ones die as a result of use

How We Distinguish Pitches (Two Theories)

Place Coding Theory: States that pitch of sound is determined by location of activated hair cells along basilar membrane; activation of receptors near base of cochlea (narrow and stiff, responds to high frequencies) signals treble, and activation of receptors near the apex (wide and floppy, responds to low frequencies) signals bass This is example of labeled lines (each neuron fires in response to particular favorite frequency) Temporal Coding Theory: states that frequency of auditory stimuli is encoded in rate of firing of auditory neurons; frequency of action potentials produced by neuron relates to number of cycles per second (hertz) of sound (ex: 500 hertz might cause auditory neurons to fire 500 action potentials per second) Encoding sound frequency within volleys of action potentials averaged across many neurons provides brain with additional source of pitch info We rely on both of these processes to determine pitch of sounds; temporal coding is most evident at lower frequencies (up to 4000 Hz); beyond about 4,000 Hz, however, pitch discrimination relies on place coding of pitch along basilar membrane

Mechanisms that Underlie Alzheimers and Reduction of Neuroplasticity

Plaque Formation: plaques are insoluble deposit of a peptide called Amyloid-Beta, or abeta, formed when a protein, called amyloid precursor protein, is sequentially cleaved by two enzymes: beta and gamma secretase Other molecules are generated by this cleavage and may play a role in the disease but abeta is the main culprit; abeta tends to misfold, become sticky, clumping together to form soluble oligomers; Some of these aggregate into large insoluble fibrils that deposit in the brain as plaques These oligomers weaken communication and plasticity at synapses, and this could be what stops the brain from forming, or retrieving memories Roles of Astrocytes and Microglia in Alzheimers: Microglia: immune cells that clear out waste and prune synapses during development Microglia take up abeta, but they also get activated by it, triggering the release of inflammatory cytokines that can damage neurons The microglia also start to remove synapses by phagocytosis As synapses start to malfunction and neurons die, abnormal patterns of activity emerge, and eventually, the brain can't process and store info properly Role of Neurodegeneration and Tau Protein in Alheimers: Another feature of Alzheimer's is neuro-degeneration; neuronal damage and death is triggered by A-beta, but some of Abeta's effects seem to be mediated by another protein in the brains of patients: tau, a component of tangles In a healthy neuron, molecules are carried along the axon on a series of tracks made of microtubules and stabilized by Tau; but in Alzheimer's tau is modified, causing it to dissociate from the microtubules, adopt an abnormal shape, and move from axon to cell body; In Alzheimer's patient, Tau sticks together and deposit as tables, and these processes eventually kill the neuron Another problem in animal models is that misfolded Tau proteins can spread across synapses into healthy neurons; there, they make healthy tau proteins start to misfold as well, spreading pathology across the brain; the pattern of spreading throughout the diff brain regions matches the changing symptoms from early to late stages of Alzheimer's; Despit

Schizophrenia

Positive symptoms (things that are there that should not be there); ex: hallucinations, delusions Negative symptoms (things that are not there that should be there); ex: lack of emotional expression, inability to experience pleasure in everyday activities Earlier signs of schizophrenia include attention and memory deficits, and impulse control (also very helpful to see if there are family members that have schizophrenia, hard to diagnose this alone) Prevalence is 0.32% female, 0.36% male population; onset tends to be in late 20s 5 different types of schizophrenia: paranoid schizophrenia is the most common type

Why More Females Than Males Develop Depression

Postpartum Depression: bout of depression immediately preceding and/or following childbirth; suggests that some combination of hormones can precipitated depression About 1/7 pregnant women will show symptoms of depression CBT is safest treatment for postpartum depression

The Vomeronasal Organ Mediates Interspecies Defensive Behaviors Through Detection of Pheromones

Potential predators emit uncharacterized chemosignals that warn receiving species of danger Neurons that sense these stimuli remain unknown Detection and processing of fear-evoking odors emitted from cat, rat, and snake require the function of sensory neurons in the vomeronasal organ

Memory Hacks

Practice retrieving info from memory, don't just re-read material Embrace errors and feedback to update your memories Block out time to focus on one class/topic to limit interference Sleep after you study to support consolidation

Integrative Model of Schizophrenia that Emphasizes the Interaction of Factors

Prenatal stress (Ex: infection during pregnancy) increases likelihood that baby will develop schizophrenia later in life If mother and baby have incompatible blood types, mother becomes diabetic during pregnancy, or baby has low birth weight, baby's more likely to develop it; This suggests that schizophrenia results from complex interaction of genetic factors and stress; each life stage has own factors that may increase vulnerability: infections before birth, complications at delivery, urban living in childhood and adulthood Gray-Matter Thinning: alternation of brain development in those with schizophrenia is indicated by acceleration of normal thinning of cortical gray matter (result of synapse rearrangement):

Long-Term Depression (LTD):

Process by which synaptic connection between neurons become weaker; it's the opposing process to long-term potentiation Thought to be important to memory formation by resetting previous synaptic changes to allow for new memories to be formed via LTP Known Mechanism by Which LTD Occurs: Best known mechanism by which LTD occurs involves the same glutamate receptors involved in LTP: NMDA and AMPA receptors; NMDA receptors are usually blocked by Mg2+ ions, which are only removed if the postsynaptic neuron becomes sufficiently depolarized, as can happen through activation of AMPA receptors; When this block is removed, Ca2+ flows into the neuron, causing further depolarization (1) While LTP occurs after brief but high-intensity stimulation of a postsynaptic neuron, LTD can be caused by prolonged low-intensity stimulation or simulation that occurs after the firing of an action potential (2) With the type of meager stimulation that causes LTD, there's not enough depolarization to cause widespread removal of the magnesium blockage of the NMDA receptors; however, there's enough stimulation to cause some NMDA receptors to allow Ca2+ to flow into cell This low level of Ca2+ is insufficient to activate the enzymes that initiate LTP, but it activates a cellular cascade that causes the removal of AMPA receptors, which: (3a) Reduces the number of glutamate receptors on the postsynaptic neuron and hence weakens the synapse (3b) LTD may also cause other changes that decrease strength of synapses, such as decrease in amount of glutamate released from presynaptic neuron, (3c) Can also involve other receptors other directors like metabotropic glutamate receptors or other neurotransmitter receptors

Skill Learning

Process of learning how to perform challenging tasks with repeated practice (ex: mirror-tracing, bike riding); There are sensorimotor skills (ex: mirror tracing), perceptual skills (reading mirror-reversed text), and cognitive skills (planning and problem-solving) Basal ganglia, cerebellum, and motor cortex are important for sensorimotor skills In general, skill learning involves a functioning striatum, motor cortex, and cerebellum ; all three kinds of skill learning are impaired in people with damage to their basal ganglia, cerebellum, and motor cortex; doesn't require the medial temporal lobe

LTM Subject to Distortion:

Process of retrieving info from LTM causes memories to become temporarily unstable and subject to disruption or alteration before undergoing reconsolidation and returning to stable status Memory Reconsolidation: the return of a memory trace to stable long-term storage after it's been temporarily made changeable during the process of recall Ex: When studying, repeated retrieval (thus reconsolidation) of stored info with feedback as to whether it was correct or incorrect enhances your learning, as opposed to merely cramming

Depression

Psychiatric condition characterized by such symptoms as unhappy mood, loss of interests, energy, and appetite; difficulty concentrating; a psychiatric disorder characterized by period of depression that alternate with excessive, expansive moods Without treatment often lasts several months Depression can be lethal, as it may lead to suicide When suicide is averted the first time it's attempted, the person is unlikely to ever try it again

Three Categories of Pain Mitigation

Psychogenic: Pharmacological: Stimulation: TENS/mechanical:

Core Set of Emotions:

Researchers believe there is a core set of basic emotions underlying more varied and delicate nuances of our feelings; Darwin claimed that aspects of emotional expression may have originated in common ancestor, as nonhuman primates have same facial muscles that humans have Emotions can be seen as evolved preprogramming that helps us deal quickly and effectively with wide variety of situations (ex: feelings of disgust for body fluids may help us avoid exposure to germs) Plutchick's Formulation of Eight Basic Emotions: Proposes that there are eight basic emotions, grouped in four pairs of opposites: joy/sadness, affection/disgust, anger/fear, expectation/surprise, with all other emotions arising from combinations of this basic array: Paul Ekman's Core Set of Seven Emotional Expressions: according to him, there are distinctive expressions for anger, sadness, happiness, fear, disgust, surprise, contempt, and embarrassment; facial expressions of these emotions are interpreted similarly across many cultures

How Stress and Emotions Affect Our Health

Psychosomatic Medicine: field that studies distinctive psychological, behavioral, and social factors that influence susceptibility or resistance to illnesses Health psychology: related field of healthy psychology emphasizes role of social factors in cause, progression, and consequences of health and illness (ex: association between heart disease and behavioral and social factors) Psychoneuroimmunology: field that studies how immune system interacts with other organs (especially those of hormonal and nervous system) There are various psychological and neurological influences in immune system (ex: people exposed to cold virus have more severe symptoms if they're experiencing conflict with others; people who tend to feel positive emotions produce more antibodies in response to flu vaccine) This suggests that both brain influences responses of immune system, and immune cells affect brain activities; Periods of elevated stress often suppress immune system (ex: in experiment, those who were stressed took 40% longer to heal-- during exam period -- than those who weren't -- during vacation and one measure of immunological response declined 68% during exam period) Long-Term Consequences of Childhood Bullying: Children subjected to verbal or physical bullying are at greater risk for mental and physical disorders when they grow up; British study followed children who were bullied into adulthood, and found that those bullied as children were at increased risk for anxiety disorders and depression, alogn with suicide:

Discovery of Lithium Therapy for Treating Bipolar Disorder (Cade 1949)

Question: do people with bipolar disorder have too much urea in circulation? Hypothesis: injecting urea into guinea pigs will make them manic Test: Found that you could dissolve higher concentrations of urea into solution if using a urea-lithium combination, lithium urate, rather than urea alone; other control guinea pigs got injections of lithium alone Results: Instead of lithium urate making guinea pigs manic, it calmed them; moreover, control injections of lithium alone were just as effective for calming the animals Conclusion: Lithium along calms guinea pigs and relieves symptoms of bipolar disorder in humans; however, lithium as narrow range of safe doses; nevertheless, lithium treatment produces relief for many people with bipolar disorder, and has increased volume of gray matter in their brains Some forms of CBT for mild cases of bipolar disorder can be as effective as drug treatments

Synaptic plasticity:

Ramon y Cahal's drawings allowed us to learn about this Physiological and/or structural changes Activity dependent and stimulus dependent; depends on what that stimulus might be (they're not all created equal, might not want to be plastic for every situation) Long term potentiation Property of all excitatory and inhibitory synapses: all of them have the capacity for change, or synaptic plasticity; this varies across development Varies across development Synaptic plasticity is the neurophysiological basis for memory

Hippocampus ("VIP" of memory research)

Really crucial for forming and retrieving episodic memories: Events that include what, where and when Hippocampal place cells help us navigate our environment and remember events in a spatial context In the maze study, if a long time goes by, and rat is exposed to new environments, you might have remapping

Various Methods of Restoring Auditory Stimulation in Deafness

Restoring Hearing Among People with Conduction Deafness: people with conduction deafness use hearing aids, which use electronic amplification to deliver louder sounds to the impaired auditory system Fused ossicles can be surgically separated or replaced with Teflon prosthetics, restoring transmission of sound vibrations to cochlea Restoring Hearing Among People with Sensorineural Deafness: mammals are incapable of regenerating hair cells; however, researchers have been able to induce birth of new hair cells in cochlear tissues of lab animals, so there is potential Cochlear Implants: treatments for sensorineural deafness focus on use of prostheses; cochlear implants are implantable devices that can detect sounds and then stimulate the auditory nerve fibers of cochlea, bypassing ossicles and hair cells and offering partial restoration of hearing; This device sends info about low frequencies to electrodes stimulating nerves at apex of cochlea and info about high frequencies to electrodes stimulating nerves at the base The earlier in life these devices are implanted, the better the person will be able to understand complex sounds

Amblyopia

Reduced visual acuity of one eye that's not caused by optical or retinal impairments; some people don't see forms clearly with one of their eyes, even though eye is intact and sharp image is focused on the retina Some people with this disorder have an eye that's turned inward or outward (cross-eyes) Children born with this see double image rather than single fused image (if untreated person reaches age of 7 or 8, pattern vision in deviated eye is almost completely suppressed; if realignment is done in adulthood, it's too late to restore acute vision to turned eye) Binocular Deprivation: depriving animals of sight in both eyes produces structural changes in visual cortical neurons: loss of dendritic spines and reduction in synapses; If this deprivation is maintained for many weeks during development, when animal's eyes are opened, it'll be blind; if deprivation lasts long enough, animal is never able to recover their eyesight Sensitive Period: also called critical period, period during development in which an organism can be permanently altered by particular experience or treatment; early visual experience is crucial for proper development of vision; These effects are most extensive during early period of synaptic development in visual cortex; after this period, manipulations have little to no effect Monocular Deprivation: Depriving only one eye of light during the developmental sensitive period; produces significant structural and functional changes in thalamus and visual cortex, permanently impairing vision in the deprived eye Ocular Dominance Histogram: the effect of visual deprivation can be illustrated graphically by an ocular dominance histogram (portrays the strength of response of a brain neuron to stimuli present to either left or right eye); In monocular deprivation, cortical neurons respond only to inputs from non deprived eye:

Distinguish the different levels of analysis for studying the biological bases of behavior - molecular to social.

Reductionism: The practice of analyzing and describing a complex phenomenon in terms of phenomena that are held to represent a simpler or more fundamental level, especially when this is said to provide a sufficient explanation; reductionist approach identifies levels of analysis that are just simple rough to examine complex phenomena Finding explanations for behavior often requires several levels of analysis, ranging from social interactions to brain systems, to circuits and single nerve cells and their even simpler molecular constituents: Levels of analysis: Molecular level Synaptic level Cellular level: (ex: single neuron) Circuit level: (ex: local neural circuit) Brain region level: (ex: visual cortex) Neural systems level: (ex: eyes and visual brain regions) Organ level: (ex: brain, spinal cord, peripheral nerves, and eyes) Social level: (ex: individuals behaving in social interaction)

How Impact of Stress can be Reduced

Relaxation Training: Involves focusing attention on something calming while becoming more aware of body, trying to relax muscles as much as possible Mindfulness-Based Stress Reduction (MBSR): Pairs relation with efforts to focus attention on present moment, including current sensations, thoughts, bodily states in a non judgemental way This practice is shown to reduce activity in the amygdala and prevent relapses in anxiety and depression

Placebo Effect

Relief of a symptom such as pain, that results following a treatment that's known to be ineffective or inert When placebo is coadministered with drug that blocks opioid receptors, people do not experience the benefits of placebo effect, suggesting that placebos work by activating brain's endogenous opioid system fMRI indicates that opioids and placebos activate same brain regions; thus, region rich in endogenous opioid receptors is more active in people who respond well to placebos

Enriched Environment and Neuroplasticity:

Research in rats has shown that simply living in a complex environment with new opportunities for learning produces biochemical and anatomical changes in the brain; in this study, rats are assigned to one of three conditions: The Impoverished condition (IC): animals are housed individuals in standard lab cages The Standard Condition (SC): Animals are housed in small groups in standard last cages (this is the typical environment for them) Enriched condition (EC): Animals are housed in large social groups in cages containing toys and other features; this provides more opportunities for learning perceptual and motor skills, social learning, etc.

Acuity vs. Sensitivity of Rods and Cones

Rods are absent in fovea, but more numerous than cones in periphery of retina (input from many rods converge in scotopic system and increase system's sensitivity to weak stimuli, but this greater convergence of rods comes at the expense of acuity as compared with the fovea **Thus, rods provide high sensitivity with limited acuity, and cones provide high acuity with limited sensitivity (why fine vision requires good lighting)

Correct Sequence of the Visual System

Characteristics of Schizophrenia

Schizophrenia: a severe psychopathological disorder characterized by negative symptoms such as emotional withdrawal and flat affect, by positive symptoms such as hallucinations and delusions, and by cognitive symptom such as poor attention span Positive Symptoms: Abnormal behavioral states that have been gained (ex: hallucinations, delusions, excited motor behavior) Negative Symptoms: Abnormalities resulting from loss of normal functions (ex:emotional and social withdrawal, blunted affect) Researchers now recognize distinction between positive symptoms (psychosis) and negative symptoms (emotional and motivational impairments) in addition to another dimension: cognitive impairment

Cortical Abnormalities in Schizophrenics

Schizophrenics differ from controls in structure and functional activity of corpus callosum; along with accelerated cortical thinning, schizophrenics tend to be impaired on neuropsychological tests that are sensitive to frontal cortical lesions; this suggested that frontal cortex activity is abnormal in schizophrenia Schizophrenics have reduced metabolic activity in frontal lobes relative to other regions of brain; this observation led to the hypofrontality hypothesis;

Role of Activation of Autonomic Nervous System in Emotion

Sensations of racing heart, warming hands, etc. are result of activation of autonomic nervous system; either the sympathetic nervous system ("fight or flight" system activating body for action) or parasympathetic nervous system (prepares body for rest and digest)

Development of Auditory Cortex With Growth and Experience

Sensitivity of auditory cortex is fine-tuned as we grow; hearing becomes more precise and rapid through exposure; as newborns develop, they get better at distinguishing sounds in languages that they hear and worse at distinguishing sounds in other languages Early experience with binaural hearing affects ability of children to localize sounds later on in life Later in life, aging deteriorates our hearing, impairing auditory cortex neurons and reduced ability to distinguish between sounds that occur simultaneously:

Animation 5.3: Somatosensory Receptive Fields

Sensory info enters the CNS via cranial and peripheral nerves, eventually reaching the thalamus, before being relayed to primary somatosensory cortex Primary sensory cortex then swaps info with the non primary sensory cortex, Each station in pathway accomplishes basic aspect of info processing Primary somatosensory cortex (S1) lies in strip of parietal lobe just behind the central sulcus Normally, the cortical region receiving info from the hand is interposed between the regions representing the upper arm and the face; These receptive fields can be mapped in animals by stimulating the body to determine which skin regions activate neurons in the S1; If electrodes are placed in the somatosensory cortex of a cat, for example, we can determine how changes in position of stimulus affect the rate of neural impulses in individual cortical neurons (ex: neuron responding to touch on a region of the forelimb) The receptive fields often include an excitatory center and an inhibitory surround, but other neurons have receptive fields with the verse composition: inhibitory centers and excitatory surrounds; When we touch outside of receptive field of an on-center sensory neuron, there's no change in the spontaneous firing rate of the cell; however, touch in the center of the receptive field excites, while touch in the surround region inhibits the cell

Other than low light, what dilates your pupils:

Stimulants and psychotropic drugs: amphetamines, cocaine, ecstacy, LSD, MDMA Anticholinergic drugs and benzodiazepines (eg anti-seizure meds), stimulants (eg: Adderall), antidepressants and anti-anxiety medication (SSRIs) Sympathetic nervous system arousal Attraction?

How Successive Levels of the CNS Process Sensory Info

Sensory info travels from sensory surface to highest levels of brain; each sensory system (touch, vision, etc.) has its own pathway from the periphery to successively higher levels of the spinal cord and/or brain Ex: (1) somatosensory touch receptors send their axons from skin to dorsal part of spinal cord, (2) upon entering the cord, somatosensory projections ascend as part of the spinal cord's dorsal column (large wedge of white matter in dorsal spinal cord); (3) These axons go all the way up to brainstem, where they synapse onto neurons that project to the opposite side and then go to the thalamus (4) From there, the incoming sensory info is directed to the cortex At all levels, inputs are organized according to somatosensory map, where body surface is divided into discrete bands; each band (called a dermatome) is the strip of skin innervated by a particular spinal nerve (this maplike organization is also feature of other sensory systems) Each station in a sensory pathway accomplishes a basic aspect of info processing (ex: painful stimulation of finger causes reflexive withdrawal of hand, mediated by spinal circuits before we even feel pain; at brainstem, other circuits turn head toward source of pain, and eventually, sensory pathways reach cerebral cortex, where the most complex aspects of sensory processing take place)

How Sensory Info Processing is Selective and Analytical

Sensory organs and pathways convey only limited (even distorted) info to the brain; a lot of the selection and analysis occurs along sensory pathways, before info reaches brain Thus, brain received highly filtered representation of external world, where stimuli critical for survival are emphasized at expense of less important stimuli This filtering happens in several aspects of sensory transduction, including stimulus coding and processing across receptive fields

The Flow of Info

Sensory organs that are perceptive the world go into our sensory buffer (representation of experience is being retained in sensory cortex), then that goes into working memory (short-term), and through the process of encoding and consolidations, you can solidify contents of working memory into long term memory, and through retrieval, we can obtain long-term memory back into working memory

Olfaction

Sensory system that detects smell; the act of smelling; our ability to perceive large number of different odors is what produces a complex array of flavors on our taste buds Odor: A sensation of smell; humans can discriminate between as many as 1 trillion different odors

Somatosensory System

Set of specialized receptors and neural mechanisms responsible for body sensations such as touch and pain As position of a stimulus is an important piece of info, somatosensory system reveals this info by the position of receptors on the sensory surface In the visual system, an object's spatial location determines which receptors in the eye are stimulated In bilateral receptor systems (ex: eyes, ears, nostrils), differences in stimulation of left and right receptors are encoded, providing brain with cues as to the location of the stimulus

Ear Physiology and Hearing/Sound Pathway

Shape of ears for collecting soundwaves (spend 15 min looking at shape of ear -- figure 6.1 -- diagram) Simple pathway: sound waves to the eardrum, to the "hammer," to the cochlea Snail shaped cochlea converts waves to electrical signals Cochlea: scala vestibuli, media and tympa In the media, you have the Organ of corti: hair cells (on the basilar membrane), supporting cells (aking to glial cells), and auditory nerve terminals Cochlea to spiral ganglion to brainstem to superior olive to inferior colliculusto media geniculate

Patient D.F.

She had some damage caused to a part of her brain that affected her vision; what part of her vision? She wasn't completely blind They watched her perform activities in a scanner; you have her Trying to identify objects visually, and on the right, when she sees something, she supposed to go and grab it;(they call it the grasperatus), where is can't move her shoulder Lateral occipital lesion = damage to ventral stream = unable to the identify objects (even a pencil) Parietal lobe fMRI activity normal during grasping = dorsal stream was ok

The stress response progresses in stages

Short study over time that measured cortisol, testosterone, epinephrine, and norepinephrine; Testosterone shows that it's not a cause of aggression; what it does is it reduces the threshold for you to experience aggression Epinephrine ramps up the sympathetic nerve panel The hypothalamic pituitary axis: adrenal fatigue; Hans Saals showed that part of reason why chronic stress is bad is because body starts adjusting to having high cortisol levels Study with packed commuter train, and stress level is normal, and an increase in epinephrine on the y-axis; starts creeping up in days leading up to exam, and then peaks during exam and goes down: Environmental stressors activate circuits differently and interact differently with variations in the body defense system: age, illnesses, financial situation, work environment, etc. Regardless, chronic stress negatively affects physical and mental health with long-term psychological consequences

How the Auditory Cortex Processes Complex Sound

Simple pure tones can be heard even after entire auditory cortex has been surgically removed; thus, auditory cortex is not involved in basic auditory perception Auditory cortex is specialized for detection of more complex, everyday life sounds containing many frequencies and complex patterns

Skin and Touch Receptors

Skin contains variety of receptors that transduce different form of energy to provide sense of touch (which is comprised of different sensory experiences--pressure, vibration, tickle, smoothness or wetness) Stimuli are recorded by receptors in skin and then transmitted along separate axons to the brain

Ruffini Corpuscles

Skin receptor cell type that detects stretching of patches of skin when we move fingers or limbs; these are sparsely distributed in the skin

Smell training for weeks to months: study showed it worked for a lot of patients infected with Covid-19

Sniff the same group of scents for 20 seconds, twice a day for three months of longer Use different scents: fruity (lemon), flowery (rose), spicy (dove), resinous (eucalyptus) Use scents you enjoyed that may bring back memories: coffee, wine,s strawberries Change up your scents every few weeks Switching your scents after several weeks may also help Avoid foods that trigger parosmia -- often meats, onions, or eggs Focus on blander food - ex: oatmeal or steamed carrots -- elss likely triggers Avoid areas with strong scents - grocery store, restaurants, perfume center Open the windows or use a fan to dissipate scents that trigger parosmia

Optic Ataxia

Spatial disorientation as a result of damage to dorsal parietal cortex; condition in which patients have difficulty using vision to reach for and grasp objects, but they can still identify objects correctly

Horizontal cells

Specialized retinal cells that make contacts among both photoreceptor cells and bipolar cells;

Stage Three: Cell differentiation:

Stage in which cells acquire distinctive characteristics, such as those of neurons, as result of expression particular genes; Newly arrived cells in brain don't resemble mature nerve cells; once the cells reach their destinations via cell migration, gene expression begins, in which cells begin to use, or express particular genes Gene Expression: the turning on or off of specific genes; the process by which a cell makes an mRNA transcript of a particular gene This stage allows cells to acquire distinctive appearance and functions of neurons characteristic of their particular regions;

Hypofrontality Hypothesis

States that frontal lobes are underactive in people with schizophrenia In discordant identical twin pairs, reduced activity of frontal cortex is evident in affected twin Hypofrontality is especially problematic during difficult cognitive tasks that depend on frontal lobes for accurate performance (ex: Wisconsin Card Sorting Task); people with Schizophrenia show little increase in their prefrontal activation during this task

Walter Canon-Philip Bard Theory of Emotion

States that it's the brain job to decide which particular emotion is appropriate response to stimuli; according to this, cerebral cortex decides on appropriate emotional experience and activates autonomic system to prepare the body (using either parasympathetic for relaxing, or sympathetic for action) Their theory insists that the brain must interpret the situation to decide which emotion is appropriate

"How Stress Affects the Brain" Video

Stress isn't always a bad thing; can be handy for an extra burst of energy, but when it's continuous, it begins to change your brain Chronic stress can affect your brain size and how it functions Stress begins with the hypothalamic pituitary adrenal axis, a series of interactions between endocrine glands in brain and kidney When your brain detects a stressful situation, your HPA system is activated and releases a hormone called cortisol, which primes your body for instant action But high levels of cortisol over long periods of time can have adverse effects; Ex: chronic stress increases the activity level and a number of neural connections in the amygdala, your brain's fear center, and as levels of cortisol rise, electrical signals in your hippocampus, part of brain associated with learning, memories and stress control deteriorate The hippocampus also inhibits the activity of the HPA axis, so when it weakens, so does your ability to control your stress Cortisol can cause your brain to shrink in size; too much of its results in loss of synaptic connections between neurons and shrinking of prefrontal cortex It also leads to fewer new brain cells being made in the hippocampus, making it harder for you to learn and remember things and set stage for more serious mental problems later The effects of stress might filter all the way down to your brain's DNA; An experiment showed that the amount of nurturing a mother rat provides its newborn plays a part in how it responds to stress later in life; pups with nurturing moms turned out less sensitive to stress bc their brains developed more cortisol receptors, which stick to cortisol and dampen stress response; pups of negligent moms had more stressful outcome (these are considered epigenetic changes, meaning that they affect which genes are expressed without directly changing the genetic code, and these changes can be reversed in the moms are swapped; The results of these actions were inheritable; There are many ways to reverse what cortisol does to stressed brain, including exercise and meditation (both of the activities decrease your stress and increase size of your hippocampus

How Receptor Cells Convert Sensory Signals Into Electrical Activity

Structure of receptor cell determines particular kind of energy or chemical it responds to; Receptor Potential/Generator Potential: While there are a wide variety of cellular mechanisms for detecting different stimuli, the outcome is always the same: electrical change in receptor (receptor potential) This is a local change in resting potential of receptor cell in response to stimuli, which may initiate an action potential; this receptor potential resembles excitatory postsynaptic potentials Sensory Transduction: The process in which a receptor cell converts the energy in a stimulus into a change in the electrical potential across its membrane; This is conversion of the signal from environmental stimuli into action potentials that our brain can understand

What's a bottom-up way (let's change the physiology on some level) to reduce anxiety?

Study (Ahles et al.): massage therapy for patients undergoing autologous bone marrow transplantation Patients in the massage group scored significantly lower on the state anxietyinventory mid-treatment (when anxiety levels are at its peak)

Anxiolytics

Substance that's used to reduce anxiety (ex: alcohol, opiates, barbiturates, and the benzodiazepines) Buspirone (Buspar): Anxiety-relieving drug that lacks the abuse potential of the benzodiazepines; this drug is an agonist at seronin 5-HT1A receptors that can provide relief from anxiety; Its effect is consistent with functional-imaging research taht reveals abnormal density of 5-HT1A receptors in brains of people with anxiety disorders

Early Studies of 'Paralytic Dementia'

Sudden onset of delusions (false beliefs held in spire of contrary evidence), grandiosity (boastful self-importance), euphoria, poor judgement, impulsive behavior These illnesses were physiologically caused by syphilis

Patient HM

Suffered from elliptic seizures that couldn't be treated with medicine; As a last report measure, a surgeon removed a large part of his brain (temporal lobes) where the seizures were originating After the surgery, HM couldn't gain any new knowledge (Facts about the world), couldn't remember new experiences from after the surgery, nor keep track of time, his age, or important life events However, HM was still able to learn new procedural skills (but no explicit memory about performing that task), holding a brief conversation, and remember old memories from before the surgery He could remember some old memories that occurred before the surgery In HM, a huge area of tissue **Overall HM had anterograde amnesia for declarative memories Hippocampus means "seahorse" and Latin

Willam James- Carl Lange Theory of Emotion

Suggests that the emotions we experience are caused by bodily changes; bodily response evokes the emotional experience (ex: we experience fear because we perceive the activity that dangerous conditions trigger in our body) Thus, different emotions feel different because they're generated by different constellations of physiological responses This theory inspired attempts to link specific emotions to specific bodily responses; however, this failed because there's no distinctive autonomic pattern for each emotion

Phenotype:

Sum of all the anatomical, psychological and behavioral characteristics that make up an individual Phenotype changes constantly throughout one's life, as it's determined by the interaction of genotypic and extrinsic (environmental) factors, including experience; Thus, individuals who have identical genotypes don't have identical phenotypes because they haven't received the same extrinsic influences

Why are the photoreceptors furthest away from the light?

Sun hits the photoreceptors first, then the bipolar cells, and then the retinal ganglion; One of the reasons that photoreceptors are furthest away from the light in this process is because they are energetically expensive (they need to be on all the time); While the bipolar cells and RGC are downstream, which means they are close to the blood supply, and they rely on the blood supply

Deep Brain Stimulation (DBS)

Surgery where delicate electrodes are surgically implanted in cingulate cortex or other brain sites; effectiveness is difficult to evaluate, because most studies have no placebo control

Summary:

Surprising reminders allow episodic memories to be modified, enabling updating or distortions; The hippocampus protects memories after expected events, but updates memories after surprising events Surprising events reset hippocampal patterns, and this reset leads to memory change **surprise creates opportunity for change; the fate of a memory depends on what comes next

Molecular Mechanisms Involved in Detection of Sweet Tastes

Sweet receptors are more like metabotropic receptors than ionotropic receptors; tastant molecules bind to complex receptor protein on taste cell's surface, which activates second-messenger within cell; there are two kinds: T1R: Family of taste receptor proteins that, when particular members bind together, form taste receptors for sweet flavors and umami flavors T2R: A family of bitter taste receptors When two members of the T1R family (T1R2 and T1ER3) combine, they make receptor that selectively detects sweet tastants

50-100 taste receptor cells in taste buds in 3 kinds of papillae (epithelial structures)

Sweet taste receptors will pick up things that are in carbs too Bitter is designed so that you can avoid it Umami will pick up things like savoriness, eggs, etc; carnivores don't have sweet receptors; tigers are carnivores and don't have sweet taste receptors The gutnick panda bears don't have umami taste receptors; they have sweet receptors

Last Three Stages of Neurodevelopment

Synaptogenesis: The creation of synapses, this is after cells have already differentiated; in order to create a synapse, the end of a neuron needs to get to its target first; In this stage, developing neurons find their targets, and target neurons and extending neurons communicate at the site of contact to create a synapse Astrocytes are very important for this process of forming synapses; they do a lot ion buffering; this was discovered by Dr. Cagla Eroglu; also really important for making sure that synapses develop efficiently The brain vastly overproduces synapses early in life; majority of increase in brain growth size comes from creating new synapses from 36 weeks of gestation - 2 years of age Majority of increase in brain size is attributable to forming of new synapses

Grapheme-color and auditory synesthesia

Synesthesia is condition in which stimulus allows person to experience an additional sensation There's activity in the color-selective region of the brain, while the brain of the non synesthete doesn't have this Behavioral tests and brains of grapheme-color synesthetes see black and white letter or numbers in color; synesthete and control both show activation in the grapheme region; only synesthete shows clear activation of hV4 (color area) Ed Hubbard has auditory synesthesia Mirror-touch synesthesia: 1.6-2.5% in general population Synesthetes experience similar sensation in the same or opposite part of the body They have higher levels of affective and pain empathy May co-occur with autism spectrum disorder Motor and sensory association cortices

Photopic System

System in retina that operates at high levels of light, shows sensitivity to color, and involves the cones; this system exhibits differential sensitivity to wavelengths, enabling color vision Compared to scotopic system, this system has less convergence (some ganglion cells report info from only one cone)

Scotopic System

System in the retina that operates at low levels of light and involves the rods; rods provide input to the scotopic system, which is very sensitive and thus works well in low light (rod vision is used to detect objects in dim light); This system is insensitive to color (thus, in darkness, only rods can detect light, and we can't tell colors apart) Convergence: there's a lot of convergence in scotopic system, as the info from many rods converges onto each ganglion cell

How Tastes Excite Specialized Receptor Cells on the Tongue

Taste Buds: A cluster of 50-150 cells that detects tastes; found in papillae; a single papilla may house several taste buds Each individual taste cells is sensitive to only one of five basic tastes (life span of 10-14 days); taste cells are constantly being replaced Papillae: Small bump that projects from surface of the tongue; contain most of the taste receptor cells; these lumps of tissue increase surface area of tongue; There are three different kinds of papillae: circumvallate (back of tongue), foliate (sides of tongue), and fungiform papillae (front of tongue); these are in different locations on tongue where there are taste receptors Microvilli: fibers that extend from taste receptor cells into a tiny pore where they come into contact with substances that can be tasted All of the five basic tastes can be perceived anywhere on the tongue The tongue also possesses sensory cells for pain, touch and temperature

Molecular Mechanisms Involved in Detection of Salty Tastes

Taste cells sense NaCl in different ways; one kind of salt sensor relies on sodium (Na+) channels; sodium ions from salty food enter taste cells via sodium channels in cell membrane, depolarizing cell and causing it to release neurotransmitter This Na+-sensing system is responsible for processing moderate concentrations of salt in food Taste cells are also sensitive to Cl- ion when salt dissolves; this parallel salf-sensing system mediates This Cl--sensing system mediates high concentrations of salt in food; drugs that block Cl- selective ion channels don't really affect the Cl- sensitivity of tongue

How Five Basic Tastes Are Signaled by Specific Sensors on Taste Cells

Tastes salty and sour are evoked when taste cells are stimulated by ions acting on ion channels in membranes of taste cells Tastes sweet, bitter, and umami are perceived by specialized receptor molecules (G-protein coupled receptors, or GPCRs) that use second messengers to alter activity of taste cell There are taste receptors in many tissues of body (not just tongue) where they control appetite and digestion

Delayed Non-Matching-To-Sample Task

Test of object recognition requiring monkeys by identifying which of two objects was not seen previously Monkeys with damage to medial temporal lobe (similar to HM) cannot perform this task

Describe the neural pathway by which information about daylight synchronizes that structure.

Textbook Info: Retinal ganglion cells send axons along the retinohypothalamic pathway, veering out of optic chiasm to synapse directly within the SCN This pathway carries info about light to hypothalamus in order to entrain rhythms; Most of retinal ganglion cells that extend their axons to SCN contain a special melanopsin, that makes them sensitive to light

Identify the sequence of steps for synaptic transmission - the steps that take place when one neuron releases a chemical signal to affect another.

Textbook Material: Action potential arrives at presynaptic axon terminal Voltage-gated calcium channels in the membrane of the axon terminal open, allowing Ca2+ ions to enter Ca2+ causes synaptic vesicles filled with neurotransmitter to fuse with the presynaptic membrane and rupture, releasing the transmitter molecules into the synaptic cleft Transmitter molecules bind to special receptor molecules in postsynaptic membrane leading (either directly or indirectly) to the opening of ion channels in the postsynaptic membrane; resulting flow of ions creates either local EPSP or IPSP in postsynaptic neuron IPSPs and EPSPs in postsynaptic cell spread toward axon hillock; if sum of all these depolarizes axon hillock enough to reach threshold, action potential will fire Synaptic transmission is terminated; message is brief Synaptic transmitter may also activate presynaptic receptor, resulting in decrease in transmitter release (by either degradation or reuptake) Degradation: enzyme in synaptic cleft break down neurotransmitter into products that can be recycled to make more neurotransmitter Reuptake: transmitter molecules may be cleared from synaptic cleft by being absorbed back into the axon terminal that released them (norepinephrine, dopamine, serotonin are examples of transmitters whose activity is terminated primarily by reuptake); special receptors called transporters are located on presynaptic axon terminal, and bring transmitter back inside

Discuss the evidence that the SCN and pineal gland govern a daily rhythm on behavior.

Textbook material: Early research showed that, in terms of the free-running rhythm of rats, large lesions of the hypothalamus interfered with circadian rhythms SCN evidence: Was subsequently discovered that lesions of a tiny subregion of the hypothalamus, the suprachiasmatic nucleus (SCN) eliminate circadian rhythms of drinking, locomotor behavior, and hormone secretion: Clocklike nature of SCN is shown by its metabolic activity; if SCN cells are removed from brain and put in a dish, their electrical activity continues to show a circadian rhythm for days or weeks, which is evidence supporting the notion that the SCN contains an endogenous clock More evidence of circadian rhythm comes from transplanting SCN from one animal to another: Transplant experiments: Adult hamsters receive SCN transplants from newborn hamsters; received an SCN from mutant hamster with period of 20 hours; when the adult hamster recovered, it didn't show its original circadian rhythm of about 24 hours, but displayed a rhythm that matched that of its donor, about 20 hours, which means that within the SCN itself, there must be a mechanism that can drive a circadian rhythm in activity (this biological clock is affected by the mutation of the gene tau) Pineal gland evidence: at night, the pineal gland secretes melatonin that informs the brain about day length Taking melatonin at bedtime, mimicking the normal nightly release of melatonin from the pineal gland helps both sighted and blind people to entrain daylight; thus, while we rely primarily on light stimulation of the retinohypothalamic tract to the SCN in order to entrain to light, our brains have enough sensitivity to melatonin that we can use that cue in the absence of info about light Deprived of light cues, spending weeks in a cave with all cues to external time removed, people show a circadian rhythm that shifts from 24 to 25 hours

Neuroplasticity:

The ability of the nervous system to change the structure and function of synapses in response to experience or the environment; also called neural plasticity

Labeled Lines

The concept that each nerve input to the brain reports only a particular type of info; Essentially, labeled lines are particular neurons that are, right from the outset, labeled for distinctive sensory experiences; action potentials in one line signal a sound, activity in another line signals a smell, and activity in other lines signal touch There are labeled lines within sensory categories too (ex: can distinguish different types of touch because skin contains variety of receptors, using some lines to signal light touch, others vibration, and other stretching of the skin

Describe the scientific method and the impact of observations on scientific investigations.

The context of our observations is critical because it begins our method for scientific investigation; it begins our bias

Pain

The discomfort normally associated with tissue damage Pain guides our behavior in several ways that minimize the risk to our bodies While short-term pain causes us to withdraw from the source, reflexively preventing further damage, longer-lasting pain encourages behavior that promote recuperation Pain-related communication (ex: grimacing, groaning, shrieking) provides warning to kin and elicits caregiving behaviors from them

General Processes That Occur During Nervous System Development:

The fate of differentiating cells depends on where in the brain the cell happens to be and what its neighbors are doing; cells in developing brain constantly send chemical signals to one another, shaping the development of each other Cell-Cell Interactions: Cells sort themselves out via cell-cell interactions, taking on fates that are appropriate in context of what neighboring cells are doing; this is the general process during which one cell affects the differentiation of other, usually neighboring, cells If cells that have not yet differentiated extensively can be obtained and placed in a particular brain region, they can differentiate in an appropriate way and become properly integrated; Stem Cells: these undifferentiated cells, called stem cells, are present throughout embryonic tissues, so that they can be gathered from umbilical cord blood, miscarried embryos, or unused embryos produced during in vitro fertilization Placing stem cells in areas of brain degeneration (such as the loss of myelin in MS or loss of dopaminergic neurons in Parkinson's may reverse degeneration as implanted cells fill in missing components)

Stage One: Neurogenesis

The mitotic division of nonneuronal cells to produce neurons (i.e. the production of neurons); neurons themselves don't divide, but cells that give rise to neurons begin as single layer of cells along inner surface of neural tube Mitosis: The cells that give rise to neurons divide in a process called mitosis, which takes place in ventricular zone inside the neural tube Ventricular Zone: Also called ependymal layer, a region lining the cerebral ventricles from which new neurons and glial cells are born

Lateral Inhibition

The phenomenon by which interconnected neurons inhibit their neighbors, producing contrast at the edges of regions; sensory receptor cells inhibit the reporting info from neighboring receptor cells (ex: the bipolar cells that relay info from photoreceptors to ganglion cells inhibit one another, so that when one bipolar cell is active, it inhibits many of its neighbors)

Heritable Component of Schizophrenia

The more closely related a person is to someone with schizophrenia, the greater are that person's chances of also developing schizophrenia; however, mode of inheritance of schizophrenia is not as simple as involving a single recessive or dominant gene; multiple genes play a role:

Stage Two: Cell Migration:

The movement of cells from site of origin to final location; as nervous system grows, cell migration follows neurogenesis, as cells move over long distances to fill out the brain

Spectral Filtering

The process by which the hills and valleys of the external ear alter the amplitude of some, but not all, frequencies in a sound; frequencies that are affected depend on angle at which sound arrives at peaks and valleys (angle varies depending on where sound is coming from) Structure of external hear provides another localization cue

Brain Self-Stimulation

The process in which animals will work to provide electrical stimulation to particular brain sites, presumably because the experience is very rewarding People receiving electrical stimulation in septum region of brain feel sense of pleasure or warmth;

How Sensory Neurons Respond to Stimuli Falling in Their Receptive Fields

The receptive field of a sensory neuron consists of region of space in which stimulus will alter that neuron's firing rate To determine this receptive field, investigators record neuron's electrical responses to a variety of stimuli to see what makes the activity of that cell change from its resting state (ex: which patch of skin must be stimulated to change activity of a particular touch receptor?) Most of these somatosensory receptive fields are doughnut-shaped, with either an excitatory center and inhibitory surround, or inhibitory center and excitatory surround These receptive fields make it easier to detect edges on objects we feel Receptive fields differ in size, shape and quality of stimulation (ex: while some neurons respond to light touch, others respond to painful stimuli, others to cooling) Experiments that trace sensory info along pathway from receptor cell to brain show that neurons at every level will respond to particular stimuli (each of these cells has its own receptive field) As each successive neuron performs more processing, the receptive fields change significantly

Retina

The receptive surface inside the eye that contains photoreceptors and other neurons; this is the layer of neurons onto which images of the external world are projected onto; Transduction: The retina turns light into neural signals in a process called transduction, which is the conversion of light to neuronal activity; for optimal vision, light from a point on a target object must end up as a point of light on the retina (rather than a blur)

Receptive Field

The stimulus region and features that affect the activity of a cell in a sensory system; consists of stimulus features that either excite or inhibit the cell Photoreceptors at Rest: At rest, both rod and cone photoreceptors continually release glutamate Photoreceptors Stimulated by Light: Upon response of photoreceptors with light stimulus, this hyperpolarizes the photoreceptors, causing them to release less glutamate; depending on type of glutamate receptor that bipolar cells possess, they will respond differently to this

Genotype:

The sum of all the intrinsic, genetic info that an individual has Genotype was determined at moment of fertilization and remains same throughout one's life

Cornea

The transparent outer layer of the eye, whose curvature is fixed; the cornea bends light rays and is primarily responsible for focusing the image on the retina; light travels in straight line, until it encounters the cornea, which refracts light rays due to its curvature (does not change shape);

We harness this knowledge of stress biology for our optimal health

The types of stressors elicit different patterns of activation in the sympathetic and HPA axes Stressors can be good and important Short-term/acute: immediate response to infection, inflammation release of adrenaline (we need that inflammatory response to kick up our T-cells to fight infections) Medium-term: days to weeks of heightened alertness and focus for class, performances, etc. Long-term/chronic: months-years; use sleep as an indicator? Stress varies peaks across day and weeks may be good, depending on stimulus Longer -- months and years -- bad Epigenetic regulation from chronic stress causes the brain's adrenal steroid receptors to increase Early experience can produce stress immunization leads to greater resilience against stress later in life Neglect or child abuse early in life leads to epigenetic change and mental health issues Neuromodulation of serotonin, an amplifier, feeling contentment/bliss/gratitude; serotonin is like an amplifier; don't want to to be too low, but don't want it to be too high Socializing and seeing people/pets that delight us Connections take work and being flexible; connections on social media is not the same

"The Truth About ECT" Video

Therapy was first used in medicine in 1938; in its early years, doctors administered a strong electrical current to brain, causing a whole body seizure during which pateints might break bones Modern ECT is very different; while patient is under general anesthesia, electrodes deliver a series of mild electrical pulses to the brain; this causes huge numbers of neurons to fire in unison; a brief, controlled seizure; a muscle relaxant keeps spasms from spreading to the rest of the body The only physical indication of the electrical flooding the brain is a twitching foot; treatment lasts for about a minute, and most patients are able to resume normal activities about an hour after each session; ECt is commonly used to treat severe cases of major depression or bipolar disorder in patients who haven't responded to other therapies, or who have had adverse reactions to medication Half or more of those who undergo treatment experience an improvement in their symptoms Most patients treated with ECt have two or three sessions per week for several weeks; some begin to notice an improvement in their symptoms after just one session, while others take longer to respond PAtients often continue less frequent treatments for several months to a year, and some need occasional maintenance sessions for the rest of their lies Modern ECT is much safer than it used to be, but patients can still experience side effects; they may feel, achy, fatigued, or nauseated right after treatment; some have trouble remembering what happened right before a session; rarely, they might have trouble remembering up to weeks and months before; for most patients, this memory loss does improve over time; Despite its proven track record, we still don't know exactly why ECT works; neurons in brain communicate via electrical signals which influence our brain chemistry, contributing to mood and behavior; The flood of electrical activity sparked by ECt alters that chemistry (ex: ECT triggers release of certain neurotransmitters); ECt also stimulates flow of hormones that may help in reducing symptoms; ECT maintenance works better when paired with medication, even in patients who were resistant to mediation before;

Hubel and Wiesel's Experiment (Discovery of Simple and Complex Cortical Cells)

They categorized cortical cells according to types of stimuli that produced maximum responses within them; Simple Cortical Cells: Cells in visual cortex that respond best to an edge or bar of particular width, orientation and location in visual field; also called bar detectors or edge detectors Complex Cortical Cells: Cells in visual cortex that respond best to bar of particular size and orientation anywhere within a particular area of the visual field, and that needs movement to make it respond actively For some, any movement in their field is sufficient, but others require motion in a specific direction Experimental Hypothesis: Cells at higher levels of visual system respond to progressively more complex stimuli Experiment: Compare receptive fields of neurons at each level, and see how they relate to one another Result: Visual cells in LGN have concentric receptive fields Visual cells in cerebral cortex may show orientation specificity, respond only to motion, or they may respond only to motion in a particular direction Conclusion: Neurons at each level of visual system combine input from neurons at lower levels to make progressively more complex receptive fields; retinal and LGN neurons respond best to spots of light on retina, while cortical cells respond best to line of particular orientation or that move in particular direction

Pain Relief by electrical Stimulation of the Central Gray Matter in Humans and Its Reversal by Naloxone (Hosobuchi, Adams, Linchitz)

They got permission to have their tissues donated b=pack to researchers post-mortem Putting some concepts together: our brains are limited by what our sensory organs, e.g., touch receptors, photoreceptors, can translate into electrical-chemical signals for our brains to make sense of, giving rise to our perception of the world -- pain, objects faces, places, etc.-- around us **movement and physical interaction too Top-down mechanisms can control perception; descending pain-control pathways: neural pathways that descend from the brain and diminish the pain signals travellin bottom-up the ascending pathways from the body to the brain Together = central modulation of sensory info

How Mammalian Studies Show That Classical Conditioning Relies on Circuits in the Cerebellum:

This study tested classical conditioning of the eye-blink reflex; when puff of air is aimed at cornea of rabbit, it reflexively blinks; This reflex can be classically conditioned; over several trials, if an acoustic tone (conditioned stimulus) precedent the air puff (unconditioned stimulus) repeatedly, a conditioned response develops in which the rabbit blinks when the tone is sounded; info about the sound of bell reaches cerebellum, and with pairings of bell and air puff, some of the synapses within cerebellum are strengthened Neural Circuit of Eye-Blink Reflex: involves cranial nerves and some interneurons that connect their nuclei; sensory fibers run along the trigeminal nerve to its nucleus in brainstem, and from there, some interneurons' axonal endings excite other cranial nerve motor nuclei, activating muscles of eyelids, causing the blink (1) Trigeminal pathway that carries info about corneal stimulation to the cranial motor nuclei also sends axons to brainstem, (2) and these brainstem neurons send axons called climbing fibers to synapse on cerebellar neurons (3) these cerebellar cells also receive info about the auditory conditioned stimulus by a pathway through auditory centers, so that info about the CS and US converges in the cerebellum (4) After conditioning, occurring of conditioned stimulus (sound) has an enhanced effect on cerebellar neurons, so they trigger eye blink in absence of air puff Studies have shown that damage to hippocampus and rest of medial temporal lobe does not have an effect on the conditioned eye-blink response; rather, the cerebellar circuit is necessary for this

Molecular Mechanisms Involved in Detection of Umami Tastes

This taste is detected by at least two kinds of receptors: Metabotropic Glutamate receptor: responds to amino acid glutamate, found in high concentrations in meats, cheeses, other savory foods Heteodimer of T1R1 and T1R3 proteins: responds to most of dietary amino acids

Three Ways of Suppressing Unimportant Sensory Activity

To maintain sensitivity to important changes in stimuli, we need to suppress unneeded sensory activity; adaption is one way in which sensory activity is controlled; we have two other suppression systems: Physically Prevent Stimuli From Reaching Sensors: ex: closing the eyes, or fact that tiny middle-ear muscles reduce intensity of sounds that reach inner ear Central Modulation Of Sensory Information: Process in which higher brain centers, such as cortex and thalamus, suppress some sources of sensory info and amplify others; this is feature of many sensory and pain pathways, and helps brain attend to some stimuli more than others

The Effect of Binaural Beats on Visuospatial Working Memory and Cortical Connectivity:

Together, there's a summation somehow, because the frequency and the tempo, that can help with your focus, attention, sleep, and ability to be more in a dream state They put people in a binaural beats experiment, and they had two diff conditions: Sat them in front of computer screen, and they looked at central fixations spot, and then it disappears, and then second screen appears, and if you are correct, you indicate "match" In second condition, if you're correct, you indicate "match" Beauchane et al. Found that 15Hz binaural beats during visuospatial working memory increase response accuracy and modified cortical networks during the task (EEG)

How Electrical Stimulation can Relieve Pain

Transcutaneous Electrical Nerve Stimulation (TENS): mild electrical stimulation is applied to nerves around the injury sites to relieve pain; it's possible that TENS closes the spinal "gate" TENS is an efficient way of stimulating adherent nerves, bringing dramatic relief lasting for hours TENS acts by releasing endogenous opioids

Vagal Nerve Stimulation

Treatment for depression that involves pacemaker that periodically applies mild electrical stimulation to vagus nerve

Role of Genetic Factors in PTSD

Twin studies of Vietnam War veterans who had seen combat showed that monozygotic twins were more similar than dizygotic twins Those who display combat-related PTSD show memory changes such as amnesia, flashbacks, and deficits in short-term memory These symptoms suggest involvement of the hippocampus (volume of right hippocampus is combat is smaller veterans with PTSD than those without it) Non Stressed twins without PTSD tended to have smaller hippocampus (suggesting genetic factors at play) Some marked hippocampal size difference is associated with markers of inflammatory processes, leading to neurodegeneration and decreased neurogenesis

Episodic Memory

Type of declarative memory that is detailed autobiographical memory; show this when you recall a particular episode in your life; involves conscious recollection of previous experiences together with their context (time, place, associated emotions, etc.) Need both functioning medial temporal lobe and neocortex

Cognitive Behavioral Therapy (CBT)

Type of psychotherapy aimed at correcting negative thinking and improving interpersonal relationships; is about as effective as SSRI treatment Rate of relapse is lower for CBT than for SSRI treatment; CBT and SSRI treatment together are more effective in combating depression than either one is alone:

Stanley Schachter-Jerome Singer Theory (Two-Factor Theory of Emotion)

Under this model, the specific emotion we experience is thought to depend on cognitive systems that assess the context (our current social, physical and psychological situation Under this model, emotional labels are attributed to relatively nonspecific feelings of physiological arousal

Intermale Aggression

aggression between males of same species is present in most vertebrates; in many species, aggressive behavior in males is adaptive for gaining access to food and mates

Mike May Getting Sight Video

Undergone surgery to repair eyes ruined in an accident involving a freak chemical explosion Light was allowed to reach his retinas after his surgery, but after 40 years in the dark, his brain doesn't recognize what his eyes can see; his repaired eyes work almost perfectly, but he can hardly see because of the age at which he lost his sight; In the surgery, doctors replaced his cornea, which protects the eye and helps it focus; the damage to his eyes kept him from making out anything; 40 years of blindness left him with a problem: after the surgery, he had no visual memory of the world; This is because, at birth, everything we see is new, and we archive the images, and build our visual memory through experience; the brain is learning to see over the 6-9 years of one's life; when Michael was blinded at three, he only just started to understand the things that make up his vision size, shape, distance, light, shade At the back of the brain, billions of cells make up our visual cortex, the processor and storer of vision If he had spent his childhood seeing, he would have learned several different cues to attune him to, for example, the different between a three-inch curb and a six-inch one; Now his adult brain has to catch up on the things he missed as a child; thus, after his surgery, inhabits a world between blindness and sight

Learning Objectives

Understand concepts of labeled lines and sensory transduction Describe several different types of receptors in the skin and the stimuli they detect Relate the concepts of receptive fields and sensory adaptation Describe the neural pathway for the system reporting touch info from the body Define pain according to the international association for the study of pain Describe and distinguish three separate components of pain experience Describe receptor cells that detect painful stimuli and the molecular receptor proteins they use Trace the neuronal pathway that transmits pain info from the periphery to the brain and the pathway the brain uses to modulate pain Discuss various methods for controlling pain, including advantages and disadvantages of each Describe neuroplasticity as a mechanism for neuropathic pain and synesthesia

perception is not a perfect replicate of what's in the world

Unlike labeled lines, the idea of trying to trace emotion to specific circuits and brain regions, and have only those dedicated pathways is not going to happen An emotion is so complex, and while perception is not a perfect replicate of what's in the world, there's an interpretation that tend to be useful for us; Comparing to this, emotions are influenced by host of factors: context, memory, your age, what you eat on daily basis; these factors aren't going to make a labeled line type of structure meaningful

Role of Stress in Risk of Developing Schizophrenia

Variety of stressful events increase one's risk (ex: schizophrenia usually appears during time in life that many people find stressful -- transition from childhood to adulthood Another risk factor is stress of city living; people living in big city are even more likely to develop the disorder; conversely, kids who move from city to country have reduced risk of developing the disorder:

Vision and Eyesight

Vision is so much more than eyesight; sight has been focus of study to understand the way that mind and body works dating back to 500 BC Vision affects the way we behave, how we communicate We recognize faces; even when faces are transformed upside down, you can still recognize it Vision and eyesight, all parts from eyeball to retina, our brain is trying to make the best guess of what's out in the world with the sensory info that we get; we're limited by the retina in the back of our eye for picking up photons of light (we can't pick up x ray or ultraviolet) With what we do see, we collect data that we can and make the best guess of that info There is parallel processing of all of this info, in addition

Results of Study

Visual cells in the LGN have concentric receptive fields Visual cells in the cerebral cortex may show orientation specificity or respond only to motion, or: They may respond only to motion in a particular direction

Flaw in Using Hierarchical Model to Explain Facial Recognition ("Grandmother Cell Theory"):

Was suggested that, through integration of enough successive levels of analysis, a particular neuron would only respond to a person's grandmother; whenever cell was excited, a mental picture of one's grandmother would arise However, a hierarchical system like this would require a vast number of cells (more than the cortex poses) to account for all the visual objects we encounter; While some neurons are activated by sight of specific faces ("Halle Berry neurons"), these neurons don't respond to specific features of the face (as would be predicted by the hierarchical model), only the whole face or most of it when present

Patterns of Brain Activation (fMRI study):

We can track moment to moment changes in brain patterns to look at neural representations over time This signal history is constantly changing the record of recent experience. Do surprising events reset these patterns? They predicted that surprising events would reset these patterns Found that hippocampal patterns gradually stabilize during videos; after video offset, full and interrupted videos look different, and interrupted videos reset signal history:

Are there pheromones in humans?

We know that we can find it in rodents, but not clear that we have them in humans Pheromones: "substances which are secreted to the outside by an individual and received by a second individual of the same species, in which they release a specific reaction, for example a definite behavior or a developmental process" (Karlson and Luscher), 1959

Presynaptic Change in LTP

When postsynaptic cell is strongly stimulated, and Ca2+ rushes through the now-active NMDA receptors, intracellular process spurs cell to release a retrograde transmitter; Retrograde Transmitter: A neurotransmitter (often a diffusible gas like nitric oxide) that's released by the postsynaptic neuron, diffuses back across the synapse, travelling back to presynaptic neuron and alters the functioning of the presynaptic neuron Retrograde neurotransmitter induces the presynaptic terminal to release more glutamate than previously, thus strengthening the synapse even more Thus, LTP causes changes on both sides of the synapse

Effect of Synchronously-Firing Neurons

When several presynaptic neurons fire at the same time, they communicate to the postsynaptic cell, depolarizing it enough that the NMDA receptors are activated to strengthen those connections; Thus, the presynaptic neurons that fire out of synchrony with the other inputs are NOT likely to depolarize the postsynaptic neurons enough to activate NMDA receptors (they drive the postsynaptic neuron to fire) Eventually, the strengthened inputs grow new, additional connections, while weakened synapses fade away

How Chronic Stress Suppresses the Immune System

While brief stress does not impair immune system (may even enhance it), longer-lasting stress has pronounced suppressive effect on immune system; In sudden emergency, temporary suppression of immune responses makes sense because stress response demands a rapid mobilization of energy; slow and long-lasting immune responses consume energy that could be used for dealing with emergency at hand; Stress of sudden encounter first suppresses immune system, conserving resources until animal finds safe haven from predator; inflammation of injuries is also suppressed until animal finds refuge While in wild, animals undergo stress for short while, any animal stressed for prolonged period dies Thus, natural selection favors stress reactions as effort to deal with short-term problem, but this becomes a detriment when extended too long:

Adult Neurogenesis:

While mammals have produced most of the neurons they'll have at birth (increase in brain weight at this type is attributable to growth in neuron size, branching of dendrites, elaboration of synapses, increase in myelin, addition of glial cells); research suggests that we are capable of generation of new neurons in adulthood (especially in dentate gyrus of the hippocampal formation) Estimated that 700 new neurons produced daily in adult human hippocampus: While these new neurons represent minority of total, they matter Birth and survival of new neurons is enhanced by exercise, social networking, environmental enrichment, and training Experimental Discoveries About Adult Neurogenesis: Studies have shown that neurogenesis enhances forms of hippocampus-dependent learning (such as spatial memory and fear conditioning); mice with genetic manipulations that turned off neurogenesis in adult brain demonstrated impairment in spatial learning)

Specific, Elongated Stimuli of Cortical Cells

While neurons from LGN send axons to cells in primary visual cortex, visual cortical cells require more specific, elongated stimuli than those that activate LGN and ganglion cells

Difference Between Pitch and Frequency

While pitch relates to our subjective perception of sound, frequency describes physical property of sounds

"How Does Your Brain Respond to Pain?" Video

While some people are distracted by pain, other people use tasks to distract themselves from pain, and those people actually do the task better when they're in pain than when they're not How can diff people be subjected to the exact same stimulus and react differently? Pain: unpleasant sensory and emotional experience associated with actual or potential tissue damage What creates perceptions of pain? When you get hurt, special tissue damage-sensing nerve cells, cale nociceptors, fire and send signals to the spinal cord and then up the brain Processing work gets done by neurons and glia (gray matter); brain superhighways carry info as electrical info from one area to another (white matter) The superhighway that carries pain info from spinal cord to the brain is our sensing pathway that ends in the cortex (part of brain that decides what to do with pain signal) Another system of interconnected brain cells called salience network decides what to pay attention to; pain signal immediately activates the salience network, and brain also responds to pain, and has to cope with these pain signals, so motor pathways are activated, to recoil from hot stove, for example; Modulation networks are also activated that deliver endorphins and enkephalins, chemicals released when you're in pain or during extreme exercise; these chemical systems help reduce pain All of these networks and pathways work together to create your pain experience, to prevent further tissue damage, and help you cope with pain The above system is similar for everyone, btu the sensitivity and efficacy of these brain circuits determines how much you feel and cope with pain; this is why some feel more pain than others, and why some people experience chronic pain that doesn't respond to treatment, while other respond well Variability in pain sensitivity isn't that different to variability in responses to other stimuli; Why does it matter that there is great variability in our pain brain circuits? There are many treatments for pain, targeting different systems; For mild pain, non-prescription medications can act on cells where the pain signals start; Other stronger pain medications and anesthetics work by reducing the activity in pain-sensing circuits or boosting our coping system for endorphins Some people can cope with pain using methods that involve distraction, relaxation, meditation, yoga, or strategies that can be taught, like CBT For some people that suffer from severe chronic pain (pain that doesn't subside months after the injury should have healed, none of the regular treatments work Traditionally, medical science has been about testing treatments on large groups to determine what would help a majority of patients, but this has usually left out those who don't benefit from such treatments Now, new treatments that directly stimulate or block certain pain sensing, attention, or modulation networks are being developed, along with ways to tailor them to individual patients, using tools like MRI to map brain pathways

Julia's Lecture (Neurodevelopment Part II):

Why study neurodevelopment? & some background: If you break the axon of a certain brain cell, you can't regenerate that axon (this is why spinal injuries are so severe) She was interested in looking at how those other neurons can compensate for this lack of regeneration Neurodevelopmental studies have so much relevance for understanding health and disease; things like anxiety, Alzheimer's Brain cells are both normal and unique; at the end of the day, a neuron is just a specialized cell; they have cell bodies and nuclei, DNA, etc. Part of what makes neurons so unique is that they grow old with you, staying with you (there are 100 billion neurons you are born with); there are 2 million red blood cells that are made every 2 seconds Developing cells (and therefore the developing brain) are really sensitive; so if you mess with them when they're trying to develop, don't Teratogen = something that interferes with a developing embryo causing abnormalities or malformation (ex: alcohol, chemicals, infections, etc.) Neural tube is most susceptible to being damaged at week 3 The greatest sensitivity to teratogens occurs between weeks:

Layers of Bodily Tissue That Arise in Embryonic Development:

Within 12 hours of egg being fertilized, single cell divides, forming small mass of homogeneous cells; within week, emerging embryo shows three distinct cell layers (beginnings of tissues of body): 1. Ectoderm 2. Neural Tube 3. Endoderm

Evaluate evidence on sleep deprivation, its impacts on an individual and on society.

Without sleep, mental function is impaired; deficit in attention and reaction time 8.5 days without sleep can cause hallucinations Total sleep deprivation in rats = increased metabolic rate, lose weight, die after 19 days on average, immune system failure Symptoms of sleep deprivation: Mental function impaired , Schizophrenia and bizarre behaviour , Hallucinations, Increase in irritability, difficulty concentrating, disorientation , Attention deficit , Speed of reaction slower , Cognitive deficits

Do distinct brain circuits mediate different emotions?

Yes, and no; not like labeled lines Self-stimulation studies reveal a large network involved in feeling; Animals provide themselves with electrical stimulation; The septum = thin membrane at midline between cerebral hemispheres; connected to the corpus callosum; part of the MFB (medial forebrain bundle) MFB = receives input from the midbrain through the hypothalamus to the forebrain; associated with brain self-stimulation

Harmonics

a multiple of a particular frequency called the fundamental (ex: if fundamental is 440 Hz, harmonics are 880 Hz, 1,320 Hz, etc.)

McGill Pain Questionnaire

a quantitative measure of pain perception that asks people to select words that tap three different dimensions of pain; researchers found that people use different types of descriptors in various forms of pain: The sensory-discriminative dimension (ex: throbbing, gnawing, shooting) The motivational-affective (emotional) dimension (ex: tiring, sickening, fearful) An overall cognitive-evaluative dimension (ex: no pain, mild, excruciating)

What is emotion

a subjective mental state usually accompanied by distinctive cognitive (thoughts), behaviors (Actions and choices), and physiological changes (autonomic--which includes your heart rate, etc.)

Visual acuity

also known as 'sharpness of vision,' visual acuity is especially fine in the center of the visual field, falling off towards the periphery; the fine structure of the retina, called the fovea, explains why acuity is best in center of visual field Fovea: The central portion of the retina, which is packed with the highest density of photoreceptors (cones in this case; rods are absent in fovea) and is the center of our gaze Reasons for High Acuity in Fovea: Fovea has high concentration of cones, absorbing an immense amount of light, which is one reason why visual acuity is so high in the fovea; Acuity is also greater in fovea in part because in this region, light reaches cones directly without having to pass through other layers of cells and blood vessels, while in rest of retina, light particle hit these upper levels without directly reaching the photoreceptors (thus, surface of retina is depressed at fovea, providing this region with direct access to light): Differences of concentrations of cones between individuals may explain individual differences in visual acuity Species Differences in Visual Acuity: ex: hawks have a high level of visual acuity, and they have narrower and more densely packed cones in the fovea Acuity is reduced in periphery of retina because both rods and cones are larger there Optic Disc of the Fovea: Where blood vessels and ganglion cell axons leave the eye (to the nasal side of the fovea); there are no photoreceptors at the optic disc, so there's a blind spot here Blind Spot: The portion of the visual field from which light falls on the optic disc

Increase in light intensity decreases the voltage (hyperpolarization)

and when this happens, the bipolar cells and retinal release glutamate; hat is the stimulus property that is causing this (bright light causes most hyperpolarization) Lux: measure of luminance (ex: in complete bright sunlight, there are 110,000 lux; outdoors on a clear day is 10,000 lux; indoor lighting closest to window is 1000; 400 sunrise/sunset on a clear day; computer screen is on average 200-500 lux) On-center and off-center bipolar cells respond differently to the glutamate release from photoreceptors; there are different kinds of bipolar cells; we are describing just two kinds here from the perspective of receptive fields; two types of bipolar cells: On-center bipolar cells; a particular bipolar cell gets really excited when there's a spot of light on its center field, because less glutamate is being released by the photoreceptor, and on-center bipolar cells are inhibited by glutamate; on-center bipolar cell is creating a bunch of action potentials because; on-center bipolar cells are active when the light illuminates in the center of the RF Off-center bipolar cells are active when the light is off in the center of their receptor field, because they are excited by glutamate, and more glutamate is released by cone (depolarized) when there's no light stimulation; off-center bipolar cells are inhibited when light illuminates the center of RF Ganglion cells respond by increasing or decreasing the frequency of their action potentials -- which gets increasingly complex (Spend at least 10-15 minutes looking this over)

Interaural time differences (ITD)

arrival of sound to the ears at different times tells you where things are Intensity differences: these are greater at higher frequencies = latency differences (time it takes) Spectral filtering: the external ear shape reinforces high r frequencies; this translates into intensity differences being greater at higher frequencies Latency differences: differences between two ears in time arrival of sounds

Testosterone in Animals

at sexual maturity, as testes begin secreting steroid hormone testosterone, intermale aggression increases in many species In seasonally breeding animals like birds and primates, intermale aggression waxes and wanes in concert with seasonal changes in levels of testosterone Castrating males to remove source of testosterone reduces aggressive behavior:

How Music Shapes Responses of Auditory Cortex

auditory cortex of trained musicians have larger response to musical sounds; extent to which musician's brain is extra sensitive to musical notes correlates with age at which they began their training in music Kids who receive intensive musical education have enhanced speech perception later in life Early musical training alters functioning of auditory cortex later; Heschl's gyrus, portion of primary auditory cortex where music is first processed, is twice as large and twice as strongly activated by music in musicians Cortical regions that process music are influenced by brain's mesolimbic reward system, attaching reward value to new music

Cross-Cultural Similarities

cross-cultural similarity is noted in production of expressions specific to particular emotions; however, facial expressions aren't unfailingly universal; Researchers found that isolated groups' identifications of emotions from facial expressions did not fully agree with those of Westerners (especially of surprise and disgust) Such subtle cultural differences suggest that cultures affect the facial display of emotion:

Stimuli

different kinds of energy (light, sound, touch, etc.) need different sensory organs to convert them into neural activity; there's a large diversity of sensory organs across animal kingdom

How the Brainstem Systems Compare the Ears to Localize Sounds

auditory system identifies where sound is coming from by analyzing two kinds of binaural cues that signal location of sound: Interaural Intensity Differences (IIDs): A perceived difference in loudness between the two ears, which the nervous system can use to localize a sound source; these differences result from comparison of intensity (loudness) at right and left ears Intensity differences occur either because one ear's pointed more directly toward sound source, or because head casts sound shadow that prevents sounds originating on one side (off-axis sounds) from reaching both ears with equal loudness (this effect is most pronounced for higher-frequency sounds) Interaural Temporal Differences (ITDs): A difference between the two ears in the time of arrival of a sound, which the nervous system can use to localize a sound source; These differences arise because one ear is always a bit closer to an off-axis sound than other ear; there are two kinds of temporal differences present in sound: Onset disparity: difference between two ears in hearing beginning of the sound Ongoing Phase Disparity: continuing mismatch between the two ears in the time of arrival of all the peaks and troughs that make up the sound wave Sound Localization at Lower Frequencies: While both types of cues are employed in sound localization, at low frequencies, no matter where sounds are presented, there is little intensity difference between the ears; thus, for lower frequencies, differences in times of arrival are primary cues for sound localization; at really low frequencies, neither cue is much help Sound Localization at Higher Frequencies: At higher frequencies, sound shadow cast by head produces significant intensity differences The various binaural and spectral cues used for sound localization converge and are integrated in inferior colliculus

Correct Sequence of the Visual System

bipolar cells, ganglion cells, LGN, V1; the 'preferred stimuli' of the neurons change as you go from the eye deeper/further into the system

Bipolar Cells

both rod and cone photoreceptors release neurotransmitter into synapses on the bipolar cells, thus controlling their activity; these are interneurons in the retina that receive info from rods and cones and then pass it on to retinal ganglion cells

Cortical magnification of retinal image

but our perception is closer to the retinal image.. There is more visual processing Our visual brain turns a flat inverted image on the retina into a 3D upright object, distorts it (cortical magnification), and gives a color, shape and depth. We see a green cup or a familiar face V1: acronym for primal visual area, also referred to as the striate cortex; it is retinotopically organized; when you look at the retina, there are very specific layers, and this is located in the occipital lobe, in the back of the brain The retina maps onto the visual cortex; What you see sent to your photoreceptors in retinotopically organized on your cortex

Damage to MT/V5

can cause akinetopsia (motion agnosia) Faces are complex stimuli that affect mood, communication, memories, decisions... Fusiform face area (FFA) in inferior temporal gyrus; If you have damage to the FFA, you can have prosopagnosia -- face blindness

Abnormally Adept Memory Recall:

case studies of those with exceptional memory suggest that without the usual process of pruning out unimportant memories, continual perfect recall can become uncontrollable, distracting, and exhausting

Blind spot

caused by absence of photoreceptors in optic disc (where optic nerves leave); there is no empty spot in the world; the brain says that it's going to fill in that gap, or blind spot, based on what's around it Cones are distributed very tightly in place called the fovea (near the blind spot), and cones are used during daytime; these help you with acuity, so they are very sharp; around the fovea, you have the highest acuity, where it's the sharpest

Psychopaths

compared with controls, psychopaths don't react as negatively to words about violence, and show blunted responses to aversive cues associated with fear conditioning Brain imaging studies suggest that psychopaths have reductions in both size and activity of prefrontal cortex

Gate Control Theory

dominant model of pain transmission that hypothesizes that spinal "gates" (modulated sites where pain can be facilitated or blocked) control signal that gets through to brain If this theory is correct, effective pain relief may depend on finding ways to keep these gates closed, thus cutting off pain signal

Four kinds of neural connections with hair cells

each relying on different neurotransmitter: IHC Afferents: convey to brain action potentials that provide perception of sounds; comprise about 95% of the fibers leading to brain IHC efferents: lead from brain to IHCs; allow brain to control responsiveness of IHCs OHC afferents: convey info to brain about mechanical state of basilar membrane, but not perception of sounds themselves OHC efferents: from brain enable it to activate a property of OHCs, making them change their length, and then brain modifies stiffness of regions of basilar membrane, resulting in sharpened tuning and pronounced ampliciation Through this, inner ear transduces vibrations from sound into action potentials; these must now leave cochlea and enter brain

Early Experience is Crucial for Vision:

early visual experience is especially crucial for learning to perceive faces (infants with cataracts that occlude vision for first 6 months of life are impaired at recognizing faces even 9 years later) These experience-dependent effects are most likely mediated by synapse rearrangement within the visual cortex

Moebius syndrome

facial paralysis or weakness caused by the underdevelopment of cranial nerves VI and VII This is rare congenital (present at birth) neurological disorder Estimated to affect 1 in 50,000 to 1 in 500,000 newborns No cause identified, but studies suggest genetic and environmental Can also affect nerves responsible for speech, chewing and swallowing Cranial Nerve VI = abducens: this affects the eye movements Cranial Nerve VII = facial: facial muscle movement Kathleen Bogart: She was experiencing the emotion of sadness, but she couldn't convey it in a socially normal manner

Transient Receptor Potential (TRP) Ion Channels

family of proteins that detect temperature changes; mice lacking gene for TRPV1 still respond to mechanosensory pain, but not to mild heat or capsaicin (chemical in spicy foods)

4% of the population have amusia/tone-deafness:

fewer frontal to temporal connections (used DTI to look at these fibers)

Monoamine Oxidase (MAO)

first antidepressants were inhibitors of monoamine oxidase, enzyme that normally inactivates monoamines in synaptic cleft

Studies have confirmed not only that some brain regions specialize in emotions, but also that the same regions may be involved in multiple emotions

one way to study neuroanatomy of emotion is to electrically stimulate brain sites and observe effects on behavior

Multiple Genes Influencing Schizophrenia

over 100 genes that influence likelihood of schizophrenia are scattered across many different human chromosomes

Synaptogenesis

part of the process of synaptic plasticity (EPSPs are important because when you measure for them, and you notice that when there's an increase in EPSPs, you have made more synapses)

Semantic Memory:

generalized type of declarative memory involving the capacity to recall words, concepts, or numbers, essential for use and comprehension of language (ex: can know meaning of word without knowing where you learned it); *Patient K.C. could acquire new semantic knowledge, but couldn't acquire new episodic knowledge; Need both functioning medial temporal lobe and neocortex

Fragile X Syndrome

genes can affect behavior (impulse control) and brain responses (fMRI); neural plasticity might be different here because of genetic mutation; in Fragile X Syndrome, the mutated Fmr1 gene on the X chromosome fMR1 gene: "Go/No Go" inhibition task measures impulse control; when you see an X don't press the button, and over time, you have to control that impulse to press it (experiment, you sit in front of a computer screen, and it flashes letters, and your task is to whenever you see a letter that's not an x, you press button; next trial, when you see an x, don't press button) Compared to controls, FXS has less impulse control, and less fMRI activity; In study of postmortem human brain tissue, revealed an increased number of dendrites Compared to controls, FXS has more and longer dendritic spines; as part of pruning is removal of synapses and death of neurons, this person thus has aberrant synaptic pruning Thus, overall, compared to wild-type (control), synapses in the mouse model of fragile x syndrome are less pruned back and longer) Genes can dictate cell migration, synaptic pruning and synaptogenesis Neurogenesis and cell differentiation requires B9/folate/folic acid; Folate is required to make amino acids for mitotic cell division and gene expression = neurogenesis CDC: to help prevent neural tube defects, all women of reproductive age should take 400 mcg folic acid per day, and eat a folate-rich diet

Two Groups of Ganglion Cells and Their Properties: Bipolar cells also release

glutamate, which depolarizes ganglion cells (stimulated on- and off-center ganglion cells then send action potentials to report "light" or "dark" to higher visual centers): On-Center Ganglion Cells: Retinal ganglion cell that's activated when light is presented to the center, rather than the periphery, of the cell's receptive field; when light is turned on, on-center bipolar cells depolarize (ecite) on-center ganglion cells Off-Center Ganglion Cells: Retinal ganglion cell that's activated when light is presented to the periphery, rather than the center, of the cell's receptive field; de-activated when light is presented to the center of its receptive field; when light is turned off, off-center bipolar cells depolarize off-center ganglion cells

Michael May's Vision Impairment:

has poor vision despite clear images entering his eye, because he was deprived of form vision (early experience), so synaptic connections within his developing visual cortex weren't strengthened by patterns of light moving across retina, and in absence of patterned stimulation, synapses between eye and brain disappeared He had normal form vision for first 3.5 years of his life before the accident, and these residual synapses allowed him to make any sense of his vision after the surgery; as an adult he still has problems distinguishing three dimensional objects or faces, as do other people who gain vision for first time as adults

The dopamine hypothesis

has some mixed support from observation in humans on dopamine receptor acting drugs Limitations of hypothesis: Can't directly measure it Drug effects are in minutes to hours, but symptoms take weeks to change; so it's not all the drug at that dopamine level Drug actions on other neuromodulators/NTs affect symptoms Dopamine antagonists (d2 receptors) reduce positive symptoms: Increase activity of dopaminergic synapses in VTA, nucleus accumbens and amygdala (reward circuit) Example: first generation antipsychotics risperidone, *clozapine -- low affinity or D2 receptors, high affinity for 5-HT2A receptors (clozapine increases dopamine in f=prefrontal cortex) Dopamine agonists can increase positive symptoms: Example recreational drugs: amphetamine, methamphetamine (block reuptake), cocaine Increase activity in prefrontal cortex

Epigenetic Factor in Schizophrenia

paternal age; children fathered by older men have greater risk of developing schizophrenia (potentially because they are product of more cell divisions than sperm of younger men, and sperm of older men have had more opportunity to a accumulate mutations caused by errors in copying chromosomes)

Vocal sounds

have a tonotopic map on auditory cortex (just like retinotopy, labeled line going through sensory cortex) People have shown that behaviorally, mothers respond more to the frequencies of their infants more after they become mothers

MT/V5

helps to process those bars when they're moving (ex: waterfall illusion)

Phenylketonuria (PKU)

heritable disorder to protein metabolism (in which the absence of an enzyme necessary to metabolize phenylalanine, an amino acid present in many foods, which leads to a toxic buildup of phenylalanine metabolites) that results in intellectual disability) Study of PKU was first time that inherited error of metabolism was associated with intellectual disability As the dysfunctional gene causes intellectual disability only in presence of phenylalanine, reducing phenylalanine consumption reduces or prevents this effect of the gene (thus, knowing baby was born with PKU doesn't tell us anything about how their brain will develop unless you also know something about the child's diet

**Key takeaway

highly interconnected circuits respond to different emotional stimuli, lead to varying physiological impacts, producing a range of emotional expressions and mental states

Range of Tastes in Humans

humans detect only a small number of basic tastes; the variety of sensations aroused by various foods are flavors rather than simple tastes, relying on sense of smell as well as sense of taste Flavors: The sense of taste combined with the sense of smell Five Basic Tastes Possessed by Humans: salty, sour, sweet bitter, and umami; these tastes are determined genetically, and there's sizeable genetic variation in strength and pleasurable qualities of the basic tastes Tastes: any of the five sensations detected by the tongue: salty, sour, bitter, sweet, and umami

Patient N.A.:

patient who, after accident, had anterograde amnesia (could not recall most events since accident, but could recall events before accident) Exhibited normal short-term memory and could gain new nondeclarative/procedural memories (long-term); however, impaired formation of declarative long-term memories

Nondeclarative Memory

procedural memory; memory about perceptual or motor procedures, shown by performance rather than conscious recollection (ex: mirror-tracing task, riding a bike); this is often nonverbal Can measure declarative memory in various animals using the delayed non-matching-to-sample task

Grandmother cell theory

idea is that there's a cell in this temporal region taht's associated with every single you know; A single neuron that responded to Luke Skywalker, written and spoken name, and also fired to the image of Yoda (there's also some specificity) The day after finding the Jenifer Aniston neuron, pictures of Lisa Kudrow fired up the neuron

Gustatory cortex

in the frontal lobe get inputs from limbic structures - amygdala, lateral hypothalamus, and prefrontal cortices (IX: gag reflex) T2Rs and T1R G coupled protein taste receptors for bitter, sweet and umami are also in the gut. Sweet and umami receptors in the gonads; this may have some explanation power for why using artificial sweeteners doesn't help with weight loss

Anterograde Amnesia:

inability to form new memories after an event (H.M. had this)

Limbic system:

includes the hippocampus: emotion, learning, attention, and olfaction, and central processing

Electroconvulsive Shock Therapy (ECT)

intentional induction of large-scale seizure; became evident that ECT could rapidly reverse severe depression, and it remains a tool for treating severe, drug-resistant depression ECT may help depression by inducing release of monoamines

Parosmia

is a distorted olfactory sensation in the presence of an odor common in Covid-19 patients: Olfactory Disorders: Quantitative Hyposmia Anosmia Qualitative (dysosmia) Parosmia or troposmia: distorted sensations in the presence of an odor Phantosmia: distorted olfactory sensations in the absence of an odor

Example from her lab:

it's not only chemicals or mutations that cause issues; another risk factor that they added was the maternal stress paradigm; kids that were born in urban environments had greater likelihood of developing autism Hypothesis: microglia that are involved in synaptic pruning might be altered to to the embryonic environment How they tested this: they got diesel exhaust particles from the EPA, and administer to pregnant mothers (to induce prenatal stress) while they're gestating, and when you look at offspring, they're pretty normal Another risk factor is maternal stress paradigm, where instead of getting normal amount of nesting material, they get less, and this mimics a lack of resources; none of the animals that are born to mom are exposed to diesel exhaust particles Finding: only male offspring of mothers stressed while carrying them have reduced sociability; there are more synapses in males of stressed mothers Conclusion: microglia are not pruning synapses in a stressed environment

Cortical Magnification Image

l Magnification Image: The fovea is 0.1% of the retinal area, and visual cortex is 8-10% of the cortical map area What you're interpreting when you're seeing an image is actually closer to the retinal image A lot of v1 cortical real estate is devoted to foveal vision Both hemispheres = a lot of information to make best guesses about what's out there

Photopigment Receptor Molecules

light particles that strike the discs of rods and cones are captured by photopigment receptor molecules Rhodopsin: the photopigment receptor molecules of rods; Cones use photopigments that are similar to rhodopsin

Neuropathic pain

phantom limb pain; neuroplasticity gone wrong Chronic phantom pain occurs in at least 90% of amputees; in 2 out of 3, it's an insatiable itch in the missing limb, many feel extreme discomfort or even chronic pain "Phantom limb pain might be caused by changes in the brain -- not, as most people thought, in the peripheral nerves near the phantom limb." Rama's patients: "When I move my normal hand, the phantom arm looks like it's moving; when I open the normal fist, the phantom hand -- whose fist I couldn't open for months -- suddenly feels as if it's opening as a result of the visual feedback and the painful cramp goes away."

Neuroplasticity

physical change of the brain that enables encoding and storing of the new information for learning skills and formation of new memories (also neural plasticity); this is NOT referring to cellular mechanisms, while neurogenesis is

Limbic System

mamillary bodies of hypothalamus, anterior thalamus, cingulate cortex, hippocampus, amygdala and fornix, and the olfactory bulb Within the limbic system, there are the MFB (medial forebrain bundle) and the PVS Medial Forebrain Bundle = reward circuit (not enough to say it's the emotional circuit); includes the hypothalamus, which informs the presence of rewards, acts on VTA (ventral tegmental area), autonomic and endocrine functions via the pituitary gland. VTA and nucleus accumbens are MFB main circuits (mesolimbic pathway); The MFB is dopamine-rich: Paraventricular System (PVS) = punishment circuit; include the hypothalamus, thalamus, central grey substance around the aqueduct of Sylvius; secondary circuits in the amygdala and hippocampus Rich in oxytocin, vasopressin, CRH, and TRH The amygdala is critical to emotional learning -- forming associations between emotional responses and specific memories of stimuli Does not very take very long for a rat, and therefore, a human, to have emotional learning; it's almost like one-trial learning; They found that lesioning the central nucleus in the amygdala prevents increase of blood pressure and freezing behavior Amygdala is also important for appetitive learning The central nucleus is separated from the lateral nucleus; stimulus picture goes to the sensory organs, the eyes, sends it to the thalamus of the relay station, and then there's a low road and a high road (low means it doesn't go to the cortex) Key regions in the humans and mouse brains involved in fear memory:

Hearing Loss

moderate to severe decrease in sensitivity to sound

Donald Hebb's Discovery:

modern ideas about synaptic plasticity originated from his theories; proposed that when a presynaptic and postsynaptic neuron were continually activated together, the synaptic connection between them would become stronger and more stable (reinforces the idea that "cells that fire together wire together) Hebbian Synapses: A synapse that is strengthened when it successfully

Repetitive Transcranial Magnetic Stimulation (rTMS)

modern technique for altering cortical electrical activity that is being developed as a treatment for depression Today, most common treatment for depression are drugs that affect monoamine transmitters: norepinephrine, dopamine, and serotonin

Myopia (nearsightedness)

most common vision problem, in which one has difficulty seeing distant objects; myopia develops if the eyeball is too long, causing cornea and lens to focus images in front of retina rather than on it Myopia can be corrected by lenses that correct refraction of image so that it's on the retina

Maplike Organization of Neurons of Visual and Touch Pathways

neurons at all levels of visual and touch pathways are arranged in an orderly, maplike manner, reflecting both spatial positions and receptor density More cells are allocated to spatial representation of sensitive, densl innervates sites (ex: lips), then to sites that are less sensitive (ex: skin on back) Each cell in sensory map responds to particular type of stimulus occurring in a particular place

Serotonin-Norepinephrine Reuptake Inhibitors (SNRIs)

new class of antidepressants, like Cymbalta and Effexor Compounds being investigated as antidepressants include glutamate receptor antagonist ketamine, a PCP-like drug that relieves depression instantly, in contrast to SSRIs and SNRIs, which take weeks

Long Term Potentiation:

occurs in the dentate gyrus of the hippocampus (synaptic plasticity); entorhinal cortex also provides input to the hippocampus Synaptic plasticity also means the apoptosis of some neurons LTP occurs at synapses that use glutamate as an excitatory neurotransmitter that bind to the NMDA and AMPA receptors to produce ESPSs in postsynaptic neurons When glutamate is released in synaptic cleft, the action potentials of the postsynaptic cells go up Glutamate is critical; her seizure medicine acted on glutamate

Sensory Adaptation

progressive decrease in a receptor's response to sustained stimulation (allows us to ignore unimportant events) Phasic Receptors: Receptor in which frequency of action potentials drops rapidly as stimulation is maintained Tonic Receptors: Receptor in which frequency of action potentials declines slowly or not at all as stimulation is maintained; pain receptors are tonic receptors, maintaining high level of activity to help us avoid injury; Process of sensory adaptation illustrates the fact that sensory systems often shift away from accurate portrayal of the external world

Paraventricular System (PVS)

punishment circuit; include the hypothalamus, thalamus, central grey substance around the aqueduct of Sylvius; secondary circuits in the amygdala and hippocampus Rich in oxytocin, vasopressin, CRH, and TRH

McGill Melzack Pain Questionnaire

qualitative differences in pain may be reflected in respondent's word choice (Melzack, 1975) The sensory-discriminative dimension (e.g., throbbing, gnawing, shooting) The motivational-affective (emotional) dimension (e.g., tiring, sickening, fearful) An overall cognitive-evaluative dimension (e.g., no pain, mild, excruciating) "High degree of agreement on the intensity relationships among pain descriptors by ..." Regardless of all these other variables, it still matched up pretty well between the doctor and the patient This takes about 15-20 minutes; patients are usually selective, rejecting words till they find the 'right; one; patients are grateful to be provided words to describe their pain

SCN9A Gene

responsible for pain sensitivity; this gene encodes sodium channel expressed in free nerve endings that serve as nociceptors

The spatial-frequency model

says that visual system analyzes the number of light-dark (or color) cycles per degree of visual space; Cortical neurons are optimized to detect light-dark cycles and respond maximally to repeating bars of light

Synapse Rearrangement:

se Rearrangement: Microglia are involved in this AKA synapse remodeling, synaptic pruning Loss of some synapses, gain of others Refinement of connections, efficiency; continues through lifetimes Weak synapses will probably be eliminated, because they're not being utilized This part is so prolonged compared to the others, these processes are happening in you now Example of synapse rearrangement in real life: weaker synapses tend to be eliminated as they're not being utilized; distinct circuit refinement due to the engulfment of synaptic inputs Microglia sculpt postnatal neural circuits in an activity and complement-dependent manner; over time, thalamus region will become really organized, and this is done based on the strength of the inputs

Amnesia

severe impairment of memory, usually as a result of accident or disease that harms/affects the temporal lobes; both retrograde and anterograde amnesia can be mild or severe Anterograde amnesia: Difficulty encoding new memories for experiences that happen after the event Retrograde amnesia:difficulty encoding memories that happened before event

Pacinian Corpuscle

skin receptor embedded in innermost layer of skin that selectively responds to vibration and pressure Acts as filter; allows only vibrations of about 200 cycles per second to stimulate sensory nerve ending inside it By stretching membrane of sensory nerve ending, stimuli cause mechanically gated sodium channels to pop open, creating a graded receptor potential; amplitude of this receptor potential is directly proportional to strength of stimulus received; If receptor potential exceeds threshold, action potentials are generated that travel via sensory nerves to spinal cord:

Kangaroo Method

skin-to-skin method; this contact helps us with thermoregulation, which is a lot better than thermoregulation through a thermostat; a lot of these chemicals can be found in different amounts in fathers, grandmothers, etc. Recommendation from pediatrics is: as soon as you have that baby, put in right on your chest; the problem is you don't do that is that they don't have that positive feedback from all of these other distractions; if you don't breastfeed, all kinds of consequences will be significantly higher There are a couple of studies that show how hugging is good

Neuropathic Pain

sometimes pain persists long after injury has healed; this is a negative example of neuroplasticity, in which neurons continue to directly signal pain and amplify pain signal in absence of any tissue damage Phantom Limb Pain: type of neuropathic pain in which patients experience significant pain that comes from amputated limb; one treatment for this is using mirror to trick brain into believing it's controlling the missing limb; here visual feedback allows brain to recalibrate pain signal:

Amacrine cells

specialized retinal cells that contact both the bipolar cells and the ganglion cells; amacrine cells are important in inhibitory interactions within the retina

Tetanus

spike of activity

Adoption Studies and Schizophrenia

studies of adopted people confirm a strong genetic factor in schizophrenia; biological parents of adoptees with schizophrenia are far more likely to have the disorder than the adopting parents are

Glutamate Hypothesis

suggests that schizophrenia results from underactivation of glutamate receptors, which accounts for reduced activity in frontal cortex However, NMDA receptor agonists are not an option, because they produce seizures; So researchers are focusing on manipulations of metabotropic glutamate receptors (mGluRs)

Facial Feedback Hypothesis

suggests that sensory feedback from our facial expressions can affect our mood, consistent with James-Lange notion that sensations from body inform us about emotions (ex: people who've been simulating a smile reportedly experience more positive feelings than participants simulating a frown)

Universal facial expressions

text says 8, Dr. Paul Ekman says 7 (FAcial action Coding System (FACS); Depending on what kinds of methods you have, you might conclude differently; While inside out has joy, fear, anger, disgust, and sadness, Ekman says that there are 7 There's a distinction between anger and disgust, between surprise and fear, is socially based, not biologically based Ekman is a cultural anthropologist; facial expressions in a New Guinea Tribesman making faces when they were told these stories Figure breaking down Western literate groups, non-Western literate groups, and then the isolated, non-literature groups For happiness, there's a lot of agreement here, but with disgust and surprise there's not too much agreement What are other influential factors to emotion perception across cultures? Words Communication style; how forthright are we in sharing that info Social interactions Cultural norms; what is it ok to show sadness, for example Exposures and surroundings; how often are you exposed by very emotionally-driven stimuli Values Are there finer differences within your culture or environment? Facial muscles are innervated by cranial nerve VII (facial expressions) and trigeminal nerve V (jaw movement)

Genetic Defect:

the absence of a particular enzyme that controls a critical biochemical step in the synthesis or breakdown of a vital body product

Biconvex Shape of Lens of Eye

the biconvex (bulging on both sides) shape of the lens of the eye causes the visual scene that's focused on the retina to be upside down and reversed compared with the real world

Ciliary Muscles

the change in shape of the lens is controlled by the ciliary muscles inside the eye; contraction of these muscles changes the focal distance of the eye, which causes nearer images to come into focus on the retina (this process is called accommodation); Accommodation: The process by which the ciliary muscles adjust the lens to bring nearby objects into focus

Pinnae

the external part of the ear; fleshy objects that most people call ears; they funnel sound waves into second part of external ear: the ear canal Pinna is distinctly mammalian characteristic; animals with exceptional auditory localization abilities have very mobile ears (ex: bats) Ridges and valleys of pinna modify character of sound that reached middle ear; some frequencies are enhanced while others are suppressed (ex: shape of ear increases reception of sounds from 2000-5000 HZ, which is a frequency range important for speech perception)

Visual Processing Begins in the Retina

the first stages of visual info processing occur in the retina (receptive surface inside back of eye that contains several distinct layers); there are cells called photoreceptors in the retina; Photoreceptors: sensory neurons in the retina that detect line; there are two types; rods and cones (these two different photoreceptors provide input to two different functional systems in the retina--the scotopic and photopic systems): Rods: A type of photoreceptor in the retina that's most active at low levels of light; that responds to visible light of almost any wavelength Provide input to the rod-based system of the retina (scotopic system) Cones: a type of photoreceptor that comes in several different varieties, respond differently to light of varying wavelengths, and thus are responsible for color vision These are less sensitive than rods, requiring more light to function Provide input to the cone-based system of the retina (photopic system)

Neurogenesis

the growth of neurons (from non-neurons) and the cellular changes are mechanisms for storing memories; structural, cellular stuff that allows us to store memories

Fundamental Frequency

the predominant frequency of an auditory tone

Three Kinds of Problems That Cause Deafness

there are three kinds of problems preventing sound waves in air from being transformed into auditory perceptions: problems with sound waves reaching the cochlea, trouble converting sound waves into action potentials, and dysfunction of brain regions that process sound: Conduction Deafness: Ear may fail to convert sound vibrations in the air into waves of fluid within the cochlea; this is called conduction deafness, and comes about when ossicles of middle ear become fused together and vibrations of eardrum can't be conveyed to oval window of cochlea Sensorineural Deafness: Even if vibrations are conducted to cochlea, the organ of Corti and its hair cells may fail to convert ripples created in basilar membrane into action potentials that inform brain about sounds; This is usually result of damage or destruction of hair cells (can be caused by genetic abnormalities, exposure to extremely loud sounds, medical infections, adverse drug effects Tinnitus: A sensation of noises or ringing in the ears not caused by external sound; long-term exposure to loud sounds can cause this Central Deafness: Occurs when auditory brain areas are damaged (ex: by strokes, tumors, or traumatic injuries); such individuals can often hear normal range of pure tones, but not perceive complex sounds Word Deafness: Selective trouble with speech sounds despite normal speech and hearing for nonverbal sounds Cortical Deafness: Trouble recognizing all complex sounds (both verbal and nonverbal); caused by rare syndrome involving bilateral lesions of auditory cortex There are few treatments for central deafness; however, electric prostheses can be used to restore auditory stimulation that's missing in conduction or sensorineural deafness

Merkel's Discs

these are skin receptor cell types that detect light touch, and are responsive to edges and isolated points on surface; Meissner's corpuscles respond to changes in stimuli, enabling them to detect localized movement between the skin and a surface

Action Potentials of Ganglion Cells:

these cells conduct action potentials; from receptor cells to ganglion cells, large amounts of info from photoreceptors converge and are compressed into the action potentials of ganglion cells; (while the retina contains 100 million rods and 4 million cones, only 1 million ganglion cells are present to transmit info to the brain)

Graded Potentials of Rods, Cones, Bipolar Cells, and Horizontal Cells

these cells in the retina generate only graded, local potentials (don't produce action potentials), thus affecting each other through the graded release of neurotransmitters in response to graded changes in electrical potentials

Photopigment Receptor Molecules

these photoreceptors' sensitivity are attributable to their structure, which consists of a stack of discs, where light particles are detected; while only a fraction of the light that strike the cornea reaches the retina, the stacking of these discs increases likelihood that one of them will capture light particles that arrive at the retina

Physical Structure of Rods and Cones

Selective Serotonin Reuptake Inhibitors (SSRIs)

these, such as Prozac, act to increase synaptic serotonin levels in brain; in rats, SSRIs increase birth of new neurons in hippocampus, which may mediate mood effects of the drugs However, there are problems with idea that reduced serotonin stimulation causes depression; it typically takes several weeks of SSRI treatment before people feel better, and this suggests that brain's response to increased synaptic serotonin is what relieves symptoms, and that response takes time; Thus, depression may originally have been caused by other factors in brain

Hair cells don't regrow,

they don't regenerate; as you get older, you start losing hair cells; as we get older, pinna gets larger vibration moves hair cells in basilar membrane

Monoamine Hypothesis

this action of MAO inhibitors causes monoamine transmitters to accumulate to higher levels in synapses, so researchers proposed that depressed people don't get enough stimulation at monoamine synapses Second generation of antidepressants (tricyclics) inhibits reuptake of monoamines, similarly boosting their synaptic activity

Cell Death

this happens through apoptosis, which is genetically programmed cell death, and this is genetically determined; some cells will express apoptotic genes Cell death is a necessary part of healthy brain development In some brain regions, what percentage of newborn neurons die before birth? Up to 50%, and in some brain regions, it's even greater than 50% What would a perturbation at this point look like? If you have an issue with apoptosis, all of those cells that are overproduced are staying; you can't get rid of all of the extra cells, and brain becomes too big for the skull Cell death regulates cortical progenitor cell apoptosis Mutant has a brain that grows too big for the skull; 20% increase in cortex How it is decided which cells survive: one way is through neurotrophic factors (NTFs) = molecules that enhance the growth and survival of neurons; once synapses are made, it becomes a competition; those neurons that don't pick up enough NTF undergo apoptosis; NTFs encourage cell survival

"Hierarchical" Nature of Hubel and Wiesel's Model of Visual Analysis

this model can be described as hierarchical, as it posits that more complex receptive fields are built up from inputs of simpler ones (ex: simple cortical cell receives input from row of LGN cells, and, in turn, complex cortical cell receives input from row of simple cortical cells):

Hubel and Weisel "map" RF

took a cat anesthetized it, lifted its eyelids, and then presented a TV screen and showed bars of light in the background, and they recorded electrical activity; depending on how they oriented the bar of light, that might activate that particular neuron, if they oriented it differently it didn't; What this tells us is that these visual neurons in our brain are specifically tuned to select for certain things in the world Neurons in higher visual areas have their own "preferred stimuli," increasingly complex; v1 helps to process the info that's received from the fovea V2, v23, etc. each one prefers specific stimuli

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